Talk:Quark/Archive 3

Archive 1

Archive 2

Archive 3

etymology

Should the article discuss the naming of the different quarks? Since the quarks have such odd names, I think many readers will wonder how they came by these names. Even if the labels are somewhat arbitrary, there still are reasons why these names were chosen. These are typically the fun factoids people try to look up in an encyclopedia. If we are going to introduce such a section we would need proper reliable sources since there is a lot of nonsense floating around on this subject. This webpage from fermmilab (physics folklore may not consitute a reliable source by itself, but the sources it cites might. Unfortunately I don't have access to any of those books. (TimothyRias (talk) 12:44, 17 July 2009 (UTC))

I disagree with an inclusion of this. The overwhelming majority of the material claims the names were almost completely arbitrary, and to claim otherwise here is almost misleading. There is no impulsion to read deeper into it. Names had to be chosen; and they were. —Anonymous Dissident^Talk 12:53, 17 July 2009 (UTC)

It is not like MGM choose "up" and "down" by random selection from a dictionary. If I recall correctly his original paper he explicitly says that "up" and "down" represent the up and down component of the isospin doublet. (interesting his third particle 's' stands for (isospin) singlet.) The reasons for calling 's' "strange" are also well documented. Charm is possibly the most random of them all, showing a Glashow and Bjorken being very pleased with their idea. Top and Bottom reflecting the fact that they mirror Up and Down also is very uncontroversial. Truth and beauty are again more random, but it should noted that these names were only introduced after the particle had being introduced as t(op) and b(ottom). There is nothing misleading about explaining where particles got their names and who gave them (although the last part is sometimes hard to track down). (TimothyRias (talk) 13:05, 17 July 2009 (UTC))

It's very clear that this is all trivia. We can hardly say in an encyclopedia article, "Glashow and Bjorken were very pleased with themselves, so they called it charm." That's why I would prefer to leave it out. Reliable sources in this area are very difficult to locate as well, and it's hard to know what to believe. Remember: verifiability, not truth. —Anonymous Dissident^Talk 13:10, 17 July 2009 (UTC)

Well apparently "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world." is a direct quote from Glashow, published in The Hunting of the Quark by Michael Riordan. I agree that it is a vague statement by the man, but it nicely illustrates how random that naming was. (As an interesting side note, he is actually talking about the charm quantum number, which in turn give its name to the corresponding quark.) This discussing this sort of thing will give a much better context for the current 'tag on' note about beauty and truth. (TimothyRias (talk) 13:37, 17 July 2009 (UTC))

Dunno about the original paper, but J.J. Sakurai in his QM textbook mentions the same reasons for the names "up" and "down". I would not object to adding a very short paragraph about the etymologies of flavor names in #Etymology (although I wouldn't use a wording such as "very pleased with themselves"). A rough sketch: "The names up and down represent the "up" and "down" components of the isospin doublet.[MGM][JJS] The strange quark is named after strangeness, a property of certain hadrons which was then explained as the presence of a strange quark;[3] according to Murray Gell-Mann, the symbol "
s
" also stands for "isospin singlet".[MGM] [Insert suitable wording for the naming of charm here.][4] Kobayashi and Maskawa originally named top and bottom quarks by analogy with up and down quarks,[KM] but the names truth and beauty, proposed by Gell-Mann, were commonly used in the past; now they have mostly fallen in disuse.[6]" (Other info about puns such as "the SM has beauty but not truth" would belong to the articles about individual flavors, if anywhere.) But that wouldn't be a vital part of the article, anyway. --A. di M. – 2009 Great Wikipedia Dramaout 13:30, 17 July 2009 (UTC)

Hmmm... that actually examplifies a lot of the misinformation out there. I don't think KM introduced the names top and bottom. Their names for the extra particles were p and λ' inline with the names used in the GIM paper (p, n, λ, p' for up, down, strange, charm). To make things worse one of the earliest uses I found of top and bottom were in a paper by MGM, who quotes Harari as having used it before. I've haven't really been able to figure out when people started using beauty and truth, but appears to be around the discovery of the b quark in 1977. (TimothyRias (talk) 13:49, 17 July 2009 (UTC))

Exactly. I implore you: leave it out. This is too wishy-washy an area. We cheapen the article and possibly introduce falsities here. The only ones we know surely and which (I think) we can source well are the top and bottom for the isospin doublets. —Anonymous Dissident^Talk 13:54, 17 July 2009 (UTC)

Additional note: I've thought about this some more. I suppose including quotes from key people to illustrate the name origins is not damaging, but we must be careful. I'll get to work on it tomorrow. —Anonymous Dissident^Talk 14:12, 17 July 2009 (UTC)

I've gone ahead and added a paragraph. I think it's long enough. All we need is a citation for Michael Riordan's book (the page number). I couldn't access it on GBooks. —Anonymous Dissident^Talk 15:07, 17 July 2009 (UTC)

Excellent. It's short enough that someone reading "Etymology" and thinking, "Why the heck should I care?" just needs to hit "PgDown" a coupla times to get to the next section header, and yet it includes everything the more curious reader will want to know (except the pun on "beauty but not truth", but that'd be way beyond the mark). Good work. --A. di M. – 2009 Great Wikipedia Dramaout 17:49, 17 July 2009 (UTC)

SM image.

The SM image suddenly doesn't show up anymore. Does anyone else have this problem? If I remove the 300px parameter, it shows up, but otherwise it doesn't.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:20, 18 July 2009 (UTC)

I had noticed that too, but I hadn't noticed about the removing the size param. I guess that's a (hopefully temporary) technical problem and am going to ask the Village Pump about this. --A. di M. – 2009 Great Wikipedia Dramaout 09:27, 18 July 2009 (UTC)

small question ;-)

Is the diameter of a quark larger than the Planck length? 4.249.3.140 (talk) 20:13, 22 May 2009 (UTC)

Yes, by orders of magnitude. A quark's diameter is ~10^-18m, while planck is 10^-35m. —Anonymous Dissident^Talk 23:39, 22 May 2009 (UTC)

The Standard Model quarks are pointlike (no spatial size) and as far as I know there is no experimental evidence to the contrary. Blennow (talk) 21:06, 24 May 2009 (UTC)

10^-18 is point-like. But it's not planck length. —Anonymous Dissident^Talk 21:36, 24 May 2009 (UTC)

No, 10^-18 is not point-like. It is very far from point-like. Point-like means no spatial extension at all, i.e., a diameter of zero. Just like all other elementary particles in the Standard Model. Blennow (talk) 22:38, 24 May 2009 (UTC)

Believe what you want. I can bring up at least a dozen sources in ten minutes supporting my assertion that quarks have a diameter of approximately 10^-18m. —Anonymous Dissident^Talk 06:00, 25 May 2009 (UTC)

Then you should probably do just that, because quarks like all fundamental particles in the standard model are pointlike objects. If the particles in the standard model would have a diameter, we would not have to worry about UV divergences en renormalisation, etc. since there would be a natural cutoff. I would not even know how to begin to define a diameter for fundemental particle, it is not like you can picture them as small hard spheres or something. The only thing that would come close would their interaction crosssection, but that strongly depends what type of particle the quark is interacting with, and also on the involved energies. So, I'm kind of curious what you mean when you say that quarks have a diameter. (TimothyRias (talk) 07:34, 25 May 2009 (UTC))

I'll just link a few for you; and that's just preliminary. —Anonymous Dissident^Talk 08:58, 25 May 2009 (UTC)

If you would have actually read that barrage of links of yours, you would know that that 10^-18m as just the experimental upper bound for the diameter of quarks. I.e. experiments have probed quarks down to 10^-18m scales and found no substructure and these results thus are consistent with the way quarks are modeled in the standard model, namely as point-like objects with zero size. (The two links that actual say that quarks are about 10^-18m in diameter are clearly talking out of their arse.) (TimothyRias (talk) 09:25, 25 May 2009 (UTC))

I don't think you've read them. A number of them state clearly, with no caveats, what I'm arguing. Concede or don't concede – I hardly care, and the IP can make up their mind for themselves. —Anonymous Dissident^Talk 09:31, 25 May 2009 (UTC)

Know what? I don't even think it's worth arguing. You're both trained physicists, and I'm just an amateur – what do I know? But those links do say that quarks are 10^-18. If I'm wrong, explain the direct way the sources are agreeing with me. Perhaps the conclusion to be made is that if quarks are finite, they are 10^-18m (approx.)? How else can the disparity here be explained other than to say there is more than one school of thought? —Anonymous Dissident^Talk 09:51, 25 May 2009 (UTC)

Well, you don't have to feel bad. The sources that say approx. 10^-18 instead of <10^-18, show that there are many people, some of them trained scientists, that have a hard time interpreting experimental results. The sources you linked that were actually written by particle physicists all agree that the 10^-18m figure is an upperbound. The other sources are mostly scientists from other fields (nuclear physics, geophysics and some relicrap) that either left out the nuance for simplicity or just misread the experimental result. Many people forget that if the result is <10^-18 this can mean anything from ~10^-19 to 0. (TimothyRias (talk) 10:08, 25 May 2009 (UTC))

This is what 10^-18 looks like .000000000000000001m. That is much, much smaller than a dot on a piece of paper that you can make with the point of a #2 pencil. Planck length has almost twice as many zeros to the right of the decimal point. I guess you can say the diameter of a quark is smaller than a decimal point, and the plank legnth is invisible compared to that. :-)

.00000000000000000000000000000000001m equals planck length. Ti-30X (talk) 04:48, 25 May 2009 (UTC)

Tim's right, 10⁻¹⁸ is the upper bound, but all elementary particles are pointlike (within the SM and probably all extensions of it, and within experimental error too). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 12:46, 25 May 2009 (UTC)

Is there anything smaller than a quark and if so, what is the smallest "thing"? Livingston 16:16, 22 July 2009 (UTC)

Quarks are believed to be point-particles (no size). If that's true, then no, since you can't go lower than no size. But there are other point particles (see elementary particles for a list of them, all of whom are thought to be point-particles as well). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:12, 22 July 2009 (UTC)

Perkins

One very tiny issue (as you know) is with the "According to Perkins" part. I really think it's needed because what is logical is a matter of opinion. We have to put quote marks around it, else it looks strange. And when we have quote marks, it's best to say straight away who is saying what. TRias seems to feel that this is "weaseling". What do you mean by that...? —Anonymous Dissident^Talk 13:40, 22 July 2009 (UTC)

The statement that the names 'top' and 'bottom' were chosen to be logical partners to 'up' and 'down' is not that controversial you can find any number of reference saying something along those lines (and we have a perfectly good one to boot). Any subjectivity of this logic lies with whoever made that choice (and nobody seems to know who that was, best I know Harari) in the first place. By presenting the statement as a quote your weaseling out of the responsibility of the statement. The fact that Perkins said that this is logical is nonnotable non-fact, this is completely irrelevant to this article, other than as a reliable source for the statement. So, if we are not going to make that statement there is also no point in presenting the quote.

Even if you want to weasel out of making the statement by putting it in quotes, it is still unnecessary to mention Perkins. It is clear that it is a quote from the ref standing right next to it. (to make this more clear you could put the ref before the period indicating it is sourcing the quote itself. Mentioning "Perkins (2000)" is a form of Harvard citation, while the rest of the article uses footnotes. (TimothyRias (talk) 14:03, 22 July 2009 (UTC))

Okay. I've decided I'm easy with it. I've resolved that we could go on all day making minor changes that are neither here nor there and that the average reader won't even notice, but that it's not worth it. The article's featured now, so that's something to be happy with, and I'm content to just leave it. —Anonymous Dissident^Talk 15:32, 22 July 2009 (UTC)

Mass

The mass section currently contains the following paragraph:

The masses of most quarks were within predicted ranges at the time of their discovery, with the notable exception of the top quark, which was found to have a mass approximately equal to that of a gold nucleus, significantly heavier than expected. Several theories have been offered to explain this very large mass. The Standard Model posits that elementary particles derive their masses from the Higgs mechanism, which is tied to the unobserved Higgs boson. Physicists hope that, in the next years, the detection of the Higgs boson in particle accelerators (such as the Large Hadron Collider) and the study of the top quark's interaction with the Higgs field might help answer the question.

citing:"New Precision Measurement of Top Quark Mass". BNL News. 2004. Retrieved 2008-09-24. The only statement that seems to be supported by that ref is that the top quark has about the same mass as a gold nucleus. In particular, it doesn't speak about the top mass being a mystery or about studying the Higgs being expected to shine any extra light on that matter. If anything it talks about the opposite: precise measurements of the top mass being needed to study the Higgs. (Because it is an important parameter in many higgs processes.) I'm somewhat curious by what is meant that "the masses of most quarks were within predicted ranges at the time of their discovery" since the standard model doesn't predict any quark masses, they are free parameters. (or rather the coupling constants of the quark fields to the higgs field are free parameters; same difference). Moreover, I don't imagine that the very low masses of the up and down were expected at first. If there is any mystery here, it is that the quark masses span 6 orders of magnitude. For this there indeed speculative ideas about broken family/generation symmetries, and it is indeed hoped that the LHC will shed some light on this. But this is not what the current ref is about, nor is it what the article is currently saying. (TimothyRias (talk) 12:44, 8 June 2009 (UTC))

I remember wondering something like that either about the current version, or about a previous version. As you say, the standard model does not predict quark masses from first principles. What I suspect might be meant here is that the quark masses indirectly enter the cross-sections for some reactions other than resonances for the quark in question. If you observe these other reactions first, you might get some limits on quark masses, to be confirmed once your beam energy is sufficiently high to produce the appropriate resonances. But that would only apply to the heavier quarks–for the lighter ones, not much time seems to have passed between postulation and resonant production. Anyway, let's tone it down to what's actually in the reference. Markus Poessel (talk) 19:34, 8 June 2009 (UTC)

The main problem here seems to be the "predictability" or "non-predictability" of the top quark mass. The simplest solution is to simply remove any reference to prediction of any kind, which I've done. Fixed? —Anonymous Dissident^Talk 07:48, 9 June 2009 (UTC)

That doesn't really solve it. The article still suggests that the large top mass is something that needs explaining. (while apparantly the other quark masses don't need explaining?) Furthermore, the article completely leaves me in the dark to what theories it is refering that could solve this 'problem'. (hence there is a problem with WP:V, as I cannot verify that statement that the theories exist). Finally, the article is still quoting the BNL PR release for the statement that scientists hope that LHC detection of the Higgs will shine further light on the size of the top mass, while it is only stating the reverse: future precision measurements of the top mass, will shine light on the value of the Higgs mass.(TimothyRias (talk) 08:45, 9 June 2009 (UTC))

Fine. All fixed. I've removed all reference to the problematic article and have used two new sources. —Anonymous Dissident^Talk 09:00, 9 June 2009 (UTC)

That is much better. I made some minor tweaks. (TimothyRias (talk) 09:39, 9 June 2009 (UTC))

In [[1]] it is stated that mass of a proton is about 20 times larger that the total mass of its quarks. In this article it is stated that the equiv. mass of proton is 938 and the total mass of its quarks - 11, ratio of about 85. Is it an explainable discrepancy? —Preceding unsigned comment added by 130.199.3.130 (talk) 04:08, 26 July 2009 (UTC)

The other article was innacurate, so I've updated it. Citations and a note explain where you get the numbers from are still needed. Might get to do that tomorrow.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:53, 26 July 2009 (UTC)

FA

I'd just like to congratulate everyone who has consistently worked on this project on a job well done. It's been a long time coming, but I feel we've raised this article to a high standard. Special thanks go out to User:Markus Poessel, User:TimothyRias, User:Headbomb, and User:A. di M.. On a related note, I'd encourage everyone to leave the article as is now. That sounds hypocritical from me, given that I did make a few wording changes after the golden star was added, but I'd like to stress that we have to stop at some point. There's really very little point in tweaking with such things as section structure (ie. at Etymology) now. The formula works – it's Featured now. Thanks, —Anonymous Dissident^Talk 12:08, 22 July 2009 (UTC)

Congratulations to everyone. Working on this article has left me with quite a few good sources and ideas that can be used to improve the up quark, down quark, strange quark, charm quark, bottom quark and top quark articles. This probably true for the rest of you as well. So, I was wondering if any of you were interested in trying to improve those article to at least GA level as well? (TimothyRias (talk) 13:15, 22 July 2009 (UTC))

Congrats to all. It's been a long process, but what a result! I'm definitely interested in working on the Up to Top quark articles. I had the goal of bringing Lepton to FA article as a follow up to quarks (after we finally resolve that CKM image thing), as it would probably be very easy to copy the structure and flow of the quark article, but I'm not closed to the idea of working on the individual quark pages as well. The individual quark articles need more work right now, so I wouldn't object to working on them first. Baryon is also a good candidate to bring to FA, and meson ain't that far away either.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:48, 22 July 2009 (UTC)

"Electron" is a GA and was unsuccessfully nominated for FAC in January; what about that one? --A. di M. 14:43, 23 July 2009 (UTC)

Seems too hard to bring to FA IMO, just way too massive in scope compared to the other articles.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:05, 23 July 2009 (UTC)

Quark decays image

The six quarks' decay modes, with mass increasing from left to right. The "intensities" of the lines are dictated by the CKM matrix. It should be noted that the decay properties are inferred from those of quarks bounds within hadrons, except in the case of the top quark which decays too rapidly to form a hadron.

OK, we need to discuss this image. To me, it is completely unclear what this figure is supposed to portray. Is it decay widths of free quarks? Is it possible decays of bound quarks? Is it the elements of the CKM matrix? I don't know because as far as I can figure out it does not accurately portray any of those. This has been an issue for a long time and it now stands as one of the last issues for this article going to FAC.

As I see it the problems with this image can be traced back to one thing: It is not properly sourced. As a result nobody is able to check whether it is correct or not. To resolve the issue we need a couple of things:

1. A good description of what this image is supposed to portray on the image description page, including a description of what data is going into the image and what methodology was to create it. (For example why is there no arrow t -> u, a process allowed by the SM but suppressed because it involves 2 virtual W's)
2. Refs for that data.

(TimothyRias (talk) 22:02, 20 July 2009 (UTC))

It should convey the elements of the CKM matrix, in the context of quark decay (single W boson). I dunno how to make #1 clearer, and the refs for #2 is the matrix itself.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:34, 21 July 2009 (UTC)

Opinions on this?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:47, 21 July 2009 (UTC)

So, the direction of the arrows in the diagram is based on the actual (hypothetical) decays of free quarks, while the strength of the arrows only reflects the size of the relevant element of the CKM matrix and ignores all the other factors that go into the decay width. I feel this is a bit weird Frankensteinian and prone to cause confusion with readers (like it did with cryptic). It would make more sense to have the arrow style be dictated by the actual decay widths of the free quarks. (Of course that would require a source giving these decay widths.) This would look a little different from the current diagram. First of all Γ(t->b) is much larger than any of the other decay widths, this would be a good place to show case that graphically. Moreover, due to the large mass difference Γ(b->u) is probably much bigger than Γ(d->u). (again my intuition, needs a proper source). (TimothyRias (talk) 09:16, 21 July 2009 (UTC))

What to the decay widths have to do with anything? The direction of the arrows is based on quark mass (high mass to low mass), and the intensities of the arrows are the coupling indicated by the CKM matrix elements.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:43, 21 July 2009 (UTC)

The fact that the description says that these are quark decay modes, will suggest to a lot of people that these are the decay widths (even to those that do not know what decay widths are.) It is very weird to be talking about decays one hand and then only show one ingredient going into the decay probability. (TimothyRias (talk) 22:24, 21 July 2009 (UTC))

How does it suggest anything with respect to decay width? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:53, 22 July 2009 (UTC)

Just take a brief step back and look at the picture as if you are seeing it for the first time. You see some quarks and some arrows between them that represent the "decay characteristics". I would think (and I believe a significant amount of readers with me) that the arrows somehow represent the probability of each decay (aka the decay width). When you then read the description and learn that it is supposed to be the magnitude of the corresponding CKM matrix element, (some) people will be confused. (TimothyRias (talk) 13:41, 23 July 2009 (UTC))

Well the two are intimately related. The CKM magnitudes squared are the probabilities of these decays happening in a "hot soup of quarks" scenario, when nothing is suppressed by kinematics. Perhaps we could frame that image in that context? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:20, 23 July 2009 (UTC)

In a hot soup of quarks the decays will go every possible way, since at high enough temperatures all the quarks are effectively massless. So that doesn't make much sense either. (Note that if we should conclude that the image needs some alterations I'm available to implement them.) (TimothyRias (talk) 15:28, 23 July 2009 (UTC))

(←) With arrows pointing both ways then? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:03, 23 July 2009 (UTC)

That would be an option. Although I fear almost nobody will be able to appreciate the nature of that context. It also possibly suffers from being highly hypothetical in nature due to the high temperature involved. (To justify the assumption that the top is massless "the soup" would need a temperature of ~ 10 TeV, since there is a somewhat general expectation of new physics beyond 1 TeV this might turn out to be a very unrealistic scenario.)

An other option would be to replace the arrows with grayscaled solid arrows with the color proportional to the actual decay widths under the (unrealistic) assumption that the quarks are free. The problem with this option is that we would to find a source that actually calculates these decay widths. Alternatively, we could do the calculations ourselves providing the details on the image description page, but that would be horrible computation that I do not look forward to (maybe I can stick it to some grad students >:)). The calculation would also entail keeping track of the decay possibilities that open up for the higher mass quarks. (one of the reasons for the high decay rate of the top is the fact that it can decay to on-shell W's.

An easier option maybe to just indicate what the most probable decays are for each quark (under the caveat that they are assumed to be free). This hierarchy of branching ratios is not that hard to deduce, if we can't source it. Changes to the image would be minimal: some changes to the wording, the b->c, and s->u would become solid lines etc. We loose some information this way, most notably the fact that s and b are more stable than you would expect based on their mass alone due to the same values of the relevant CKM elements. (TimothyRias (talk) 08:50, 24 July 2009 (UTC))

Let's keep the image qualitative. It's meant to give a "visual feel" of the matrix. It should illustrate (for say a c quark) that in a hot quark soup, the c will change into an s most of the time, into an u some of the time, and into a t once in a blue moon. Another possibility is that we bite the bullet and use the term we're trying to avoid (coupling strength).Headbomb {^ταλκ_{κοντριβς} – WP Physics} 21:37, 24 July 2009 (UTC)

Yes, we could do that. Proposed changes: image heading: Quarks -> Quark weak interactions; lose arrowheads; legend: interaction strength, powerful, moderate, weak. Completely lose all mention of decays. How about that? (TimothyRias (talk) 09:17, 27 July 2009 (UTC))

I'd go further and even lose the heading. We can start the caption with "The strength of the weak interactions of quarks" or something similar. The only thing I don't like is the powerful/moderate/weak divisions, they don't have the right connotations. The right ones are strong/weak/weaker, but then there's confusion with a big/small coupling strengths and the strong/weak interactions. I say let's change everything but the strong/weak/weaker for now, so we can at least start fixing the image and its caption.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:29, 27 July 2009 (UTC)

The strengths of the weak interactions between the six quarks. The "intensities" of the lines are determined by the elements of the CKM matrix.

OK,how about this then. I've implemented the changes above. Furthermore, I've cleaned up the image (and the SVG code) to hopefully make it a little easier on the eyes for those of us with high DPI displays. I've gone with interaction strength: strong/moderate/weak, hopefully having the word 'moderate' there will limit confusion with 'strong interaction' and 'weak interaction'. (TimothyRias (talk) 10:04, 29 July 2009 (UTC))

That looks great!Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:42, 29 July 2009 (UTC)

Further tweaks on the image could be centering "Interaction Strength" in the box (small s in strength?), and decapitalizing Up-type and Down-type. I would also use a dotted line (instead of a spacier dashed line) for the weak line, to further enhanced the visual difference between the moderate/weak lines. Finally, the udcstb labels do not seem to be centered in their respective balls. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:33, 29 July 2009 (UTC)

Done. How does it look?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:01, 29 July 2009 (UTC)

OMG inkscape raped my pretty SVG :( (TimothyRias (talk) 19:34, 29 July 2009 (UTC))

What exactly has been raped? It looks all nice and purrrdy on this end? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:08, 30 July 2009 (UTC)

Compare the source code of my original upload with that of the current version and you might see why i'm sad. Especially if you consider that I usually edit SVGs with a text editor. (TimothyRias (talk) 05:51, 30 July 2009 (UTC))

Ah, well I can't see the source code (don't know how). Feel free to take your version and redo my changes in a non-rapist way. They should all be pretty apparent, except the removal of a duplicate line from s to t, and the centering of the udcstb labers withing their respective balls. I recall some diagonal lines not being of the same length and have to copy-paste the appropriately lengthy ones, but that might have been another image. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:56, 30 July 2009 (UTC)

(off-topic:To see the source code just open the SVG in any text editor.) (TimothyRias (talk) 10:26, 30 July 2009 (UTC))

How about this caption?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:28, 29 July 2009 (UTC)

I would leave out the middle sentence. It is very cryptic even if you what is about. (It is also partially wrong, the V_ts and V_tu components are (currently) impossible to get straight from top decay and are currently obtained through precision measurements of processes involving virtual top quarks. Kaon decay?) It is enough to say that are the intensities are obtained from the CKM matrix, how exactly those matrix elements are measured is discussed in the PDG ref and is well beyond the scope of this article. (TimothyRias (talk) 19:41, 29 July 2009 (UTC))

Alright, so this version is fine for the article?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:09, 30 July 2009 (UTC)

I think so. (TimothyRias (talk) 05:46, 30 July 2009 (UTC))

Uploaded.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:07, 30 July 2009 (UTC)

The strengths of the weak interactions between the six quarks. The "intensities" of the lines are determined by the elements of the CKM matrix.

I found an issue with the previous image. It suggested that the cd and cb couplings were virtual identical. I've created an alternative version to correct this issue by making all lines solid and having the color determined by the actual CKM values. I also created the SVG to actual be 271px wide to create less fringes on that resolution. (TimothyRias (talk) 10:26, 30 July 2009 (UTC))

An interesting take. For it to work however, we'd need to have a white (Vij=0, weak) to black (Vij=1, strong) gradient instead of three distinct level (black gray white-ish). (See the thing on the right of this plot if i am unclear [2]). The udcstb labels are still not centered within their balls. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:16, 30 July 2009 (UTC)

Added a gradient. Also, in a less-is-more spirit I've done away with the "interaction strength" text, leaving more space for the other elements. The labels look centered to me now. (also fuck buggy rSVG rendering engine used by MediaWiki). I'll check it on my other PC with a much higher DPI screen if this is legible, otherwise there is some room for increasing the font size. (TimothyRias (talk) 15:54, 30 July 2009 (UTC))

Great. Dunno what you did with the labels, but it looks good now. I'll switch the image in the main article, and we can finally move on to another one (see section about the next article somewhere on this talk page). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:01, 30 July 2009 (UTC)

Actually, aren't you an Administrator? We should merge the histories of all versions of this image.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:03, 30 July 2009 (UTC)

No, not unless somebody made admin while I wasn't looking.:) (TimothyRias (talk) 20:08, 30 July 2009 (UTC))

Repeated linking of same terms

I've noticed some inconsistency in the linking of technical terms already linked in previous sections. For example, in "Classification" we link "electric charge" but not "spin", and in "History" "bottom quark" and "top quark" are linked but none of the other flavours is. Now, the "canonical" way of only linking a term the first time it occurs in the whole article is way too drastic, because not everyone reads the article entirely from the top to the bottom. OTOH, randomly deciding to link some terms and not others is weird, and linking technical terms whenever they occur is overlinking.

An idea could be to link each relevant term only the first time it occurs in the article, except "specialistic terms" which should be linked the first time they occur in each section, where by "specialistic term" I mean a term that most people with a high school diploma have never heard of. (So "electric charge", "gold", "Big Bang" and "point-like"/"point particle" would not be "specialistic terms", but "gluon" and "quantum chromodynamics" would.) What do you think? (BTW, what's the point of "See also" templates at the beginning of sections whose very first sentence contains a link to the same article?) --A. di M. 14:22, 26 July 2009 (UTC)

I'd agree with that linking rational. The see also section are there because they either point to the main articles, or to topics of high-relevance relative to all the links found in that section.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:37, 26 July 2009 (UTC)

Quark as 15 September 2009's TFA

Since it's Gell-Mann's 80th birthday, why not? Comments can be left on the TFA request page (click on the header to get there). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:03, 15 August 2009 (UTC)

Apparently I have to wait a few days before nominating, so I removed it for now and will re-add in about a week time. I'll update this page when I do so.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:08, 16 August 2009 (UTC)

Alright, resubmitted. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:46, 25 August 2009 (UTC)

Do quarks exist?

Hi,

I just wanted to ask if quarks really exist.

I know this sounds like a but of a silly question, but I was recently reading a book by physicist Fritjof Capra, called "The Tao of Physics", and in the book he talks a lot about modern atomic physics, and he mentions a lot of quantum theories, including the quark theory, the s-matrix theory, the bootstrap theory, and the quantum electrodynamic/chromodynamic theories.

However, he mentions quite explicitly that there is no real reason to believe that quarks per se exist as actual fundamental particles. He says that it is a good theoretical model that explains a lot about our experimental observations, but no quarks have been observed, and no other particles have been known with a charge which is a fraction of that of the electron.

I also found this article on the internet: http://www.springerlink.com/content/87g2503m3754t066/ and in Andrew Watson's "The Quantum Quark", he mentions that

Gell-Mann himself argued that quarks, with their controversial properties, couldn't be seen individually, but only as composites having the better-behaved properties of particles such as protons and neutrons. In this way, fractional electric charges and baryon numbers were not "real" as such. [..] Is [the quark] a particle that experimenters can look for, or is it some mythical mathematical device useful for explaining a bit of group theory? (p.163, Cambridge University Press 2004) (also here: http://books.google.com/books?id=ip50x8IOfnEC&lpg=PA163&ots=uVzweNevmN&dq=quarks%20are%20not%20real&pg=PA163#v=onepage&q=&f=false )

"The Tao of Physics" was written in 1975, but it was revised and an afterword was written in 1995 so I would assume the information in it would be quite accurate, but it clearly might be wrong (more recent experiments might have discovered quarks).

If it is not certain that quarks really exist, is there a reason why by reading the wikipedia article one gets the impression that quarks are real, physical, fundamental particles, and not just part of a theory?

Of course I may be wrong, and quarks might have actually been physically observed in experiments, so please forgive me and correct me. (I don't have any reason to support or refute any of the theories, so I would be equally happy if someone provided links to articles which showed that experimental evidence of quarks exists.)

Thanks a lot :)

Jujimufu (talk) 09:28, 30 August 2009 (UTC)

This view was indeed very popular in the early days of the quark model and persisted deep into the 1970's. Since then quarks have become excepted as physically real objects. This is evidenced by many experimental observations ranging from the deep inelastic scattering experiments in the 1960's revealing that there must be some sort of partons later identified as quarks, formation of jets in high energy collisions, to the strong indications for the existence of a quark-gluon-plasma phase containing free quarks at high temperatures. Most of these are actually mentioned in the article. (TimothyRias (talk) 11:08, 30 August 2009 (UTC))

As TRias says, that view is quite obsolete. There is hard empirical evidence for quarks now, contrary to what your source says. —Anonymous Dissident^Talk 06:13, 15 September 2009 (UTC)

Yes. Also Gell-Mann has repeatedly been taken out of context in what he meant. He said he always considered them physical, but unobservable as free particles. This was interpreted by people who believed them to be mere mathematical artifacts to mean that he too thought of them to be nothing more than mathematically convenient, but not necessarily physical things. Communication being what it was in the the 1960 and 1970s, this idea that Gell-Mann didn't think of them as real entities spread around for a while. And since old ideas die hard, people still say that Gell-Mann didn't think they really existed or something. Of course, Gell-Mann's opinion on it is really irrelevant to whether or not they actually exist, but today I don't think anyone sees quarks as being any less real then electrons. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:28, 15 September 2009 (UTC)

Yes, Gell-Mann's opinions are irrelevant, except historically. But the reason why " people still say that Gell-Mann didn't think they really existed or something" is because he vacillated in the original article, saying (I paraphrase) that quarks "may be considered" as real. I think it was Zweig who said that Gell-Mann was trying to have his cake and eat it - i.e. covering himself if they didn't exist, yet ready to take the credit if they did - and it worked :-) .

important query ^_~

i'm pretty sure i saw this as a featured article not too long ago. whats up w that? ~_~ ~ —Preceding unsigned comment added by 68.198.35.90 (talk) 02:27, 16 September 2009 (UTC)

Ne'eman part in the QM

The history section conclude that Ne'eman independently formulate a scheme which is identical to the eight fold way (before Gal Mann actually, it's not mentioned here) but that he take no part in the subsequent proposal of the QM. This is factualy wrong, and if someone insist that such statement to be included (while in any case it's unneeded) he/she have to source it.

Ne'eman demonstarated before Gall Mann how practical proprties can be explained by symetry group SU3. Especially he showed how 8 Baryons can represent both neutrons and protons and anticipated the QM. If you claim otherwise, source it.--Gilisa (talk) 07:29, 15 September 2009 (UTC)

Article says Gell-Mann in the early 1960s (Gell-Mann worked on this since 1961 actually, but only published in 1964), and Ne'eman in 1962. I fail to say how this is not mentioning that Ne'eman came up with the Eightfold Way (who'se first is a matter of how you count, time of idea, or time of publication). Concerning the other thing, the quark model is from Gell-Mann and Zweig, not Ne'emann. The original articles from Gell-Mann and Zweig are given, plus the later article by Carithers et al. That's on top of all the other sources used in the article. I really don't know what more you could want. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:34, 15 September 2009 (UTC)

I'm out of my revert quotas on this topic, so if someone else could restore this, it would be nice. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:46, 15 September 2009 (UTC)

Well, it's only by the time of publication, meaning that Ne'eman should be mentioned first if you think on it. About the idea any one can tell anything he want others to think, it's obvious and there is no question here. Ne'eman started to work on the idea on the early 1960s and I deeply believe (after hearing the all story from late Ne'eman himself-but it's off the record of course, no original research intend) that he was the first. Actually, many think so. You argue that Ne'eman didn't anticipated the Quark model, so the burden of providing adequate source to support it is on your back (and you wrote that there are few in this article-so, please introduce one that indicate that in none of Ne'eman publications he anticipated the QM). --Gilisa (talk) 08:00, 15 September 2009 (UTC)

Do I also need to show that Lee Smolin didn't develop the Quark Model? Gell-Mann and Zweig proposed the quark model. What Ne'eman did is proposed the Eightfold Way. We're saying that he was not involved in the quark model to prevent confusing, since the Eightfold Way and Quark Model are related, but not the same things. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:12, 15 September 2009 (UTC)

You don't have to explain me what the QM is. You do have to source your claim that Ne'eman didn't anticipate the QM. The comparison to Smolin is funny.--Gilisa (talk) 08:14, 15 September 2009 (UTC)

Gilisa, it's on you to demonstrate that Ne'emon did propose the quark model, not on us to demonstrate that he didn't. All the sources I've seen have only gone so far as to say that Ne'emon was involved in the eightfold way. It's ridiculous to ask us to find sources stating that Ne'emon specifically didn't contribute – literature, in general, makes a point of noting what did happen, not what didn't. I'm restoring the old version. —Anonymous Dissident^Talk 08:18, 15 September 2009 (UTC)

Anonymous Dissident, you don't seem to get simple facts in scientific writing: The burden of eveidence is on the one who make an argument and not on the one who say that it's not accepted unless proved otherwise. The work of Ne'eman is mentioned and the notification that he didn't took part in the subsequent proposal of the QM is redundant at the least. So, provide source if you want to include this pointless statement.--Gilisa (talk) 08:24, 15 September 2009 (UTC)

Your argument makes no sense: if it's redundant, that implies it's already a given. If it's already a given, why should we source it? It either needs a source or it's redundant, not both. —Anonymous Dissident^Talk 08:35, 15 September 2009 (UTC)

My argument make strong sense, stop joking please. You don't seem to understand simple thing: It's pointless because there is no argument in the article he proposed the QM itself. I think it's pointless and hence delete it. I said that if you think it isn't-source it. I'm against this statement unless it's supported by source (even if it would still remain pointless by me).--Gilisa (talk) 08:40, 15 September 2009 (UTC)

I'm not joking. Re-read what I said. Something cannot be both pointless and requiring of a source. —Anonymous Dissident^Talk 09:18, 15 September 2009 (UTC)

Oh yes it can. It is pointless as I see it, for some reason it's probably not for you-so please provide source. --Gilisa (talk) 09:29, 15 September 2009 (UTC)

Please see the new wording, now it makes it clear that there is no intention to argue that Ne'eman suggested the QM itself (and it's not sure at all btw) and there is absolutly no need to explicitly indiacte it. For now let it stay like this. --Gilisa (talk) 09:51, 15 September 2009 (UTC)

Constituent particles

If Protons, Electrons, neutrons, and so on are made of quarks... do we know what quarks themselves are made up of? RingtailedFox • Talk • Contribs 06:53, 15 September 2009 (UTC)

As the article notes, quarks are point particles – they have no constituents. They are the fundamental constituents, according to the Standard Model. —Anonymous Dissident^Talk 07:06, 15 September 2009 (UTC)

Also, electrons are not made of quarks, rather they are leptons - elementary particles of their own. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:09, 15 September 2009 (UTC)

<prophet mode>The standard model will be standard but it's likely wrong. In my opinion quarks don't exist as particles. There's nothing "physical" at the base level, only perturbations propagating through an isotrope medium constituting the fabric of space-time itself. We measure such perturbations as either matter or energy. Quantum loop gravity has it almost right -- almost.</prophet mode>

Yeah, empirical evidence never counted for much anyway...</sarcastic mode> —Anonymous Dissident^Talk 13:29, 18 September 2009 (UTC)

1961 vs. early 1960's and 1962

Headbomb and Anonymous Dissident,the 8fold way was published by Ne'eman in 1961. There is agreement on this among all sources and 1962 is factually false date. Hence, any reversion just because 1961 is "too" specific date in compare to 1962 or "early 1960's" is baseless at best.[3]. In fact I just made the first paragraph accurate, something it wasn't so far and added adequately sourced necessary details.--Gilisa (talk) 21:00, 15 September 2009 (UTC)

You are correct about the date. I still think the earlier phrasing is best, though. Can we agree to leave things as they are now? —Anonymous Dissident^Talk 21:58, 15 September 2009 (UTC)

No, I also provided sources for everything I claim but you "still think the earlier phrasing is best" and revert in incivil way and without providing no source to support your actions, leading to edit war for a reason I yet didn't figure out but if you do it again then I will have heavy doubts about your neutrality. Your reverts actually violate WP:VAND and will be treated at least by me as such if you do it again.--Gilisa (talk) 05:37, 16 September 2009 (UTC)

Don't you dare label my contributions to this article vandalism. Do not revert again. Your edits are against consensus. It is you who will be reverted. The statement is now well-sourced and entirely incontrovertible. And do not question my neutrality. It is you who has caused all of this problem with Ne'eman. —Anonymous Dissident^Talk 06:13, 16 September 2009 (UTC)

Your incivility is not my problem any more nor does your vandl actions here.--Gilisa (talk) 06:48, 16 September 2009 (UTC)

I see that you've been blocked for edit-warring. It's an unfortunate outcome, and I think it's a shame it came to that. I really don't see why you're taking issue with the current version of the article – Ne'eman is now noted as having proposed his Eightfold Way in 1961. This was what you originally asked for. It seems to me you may have a point of view that is affecting your edits to the article; an inspection of the history is revealing of the fact that you're determined to place undue weight on Ne'eman's contribution and presenting the (non-neutral) view that he was more deserving of recognition for the quark theory than Gell-Mann. From your version (now undone): "The Technion credited Ne'eman with discovering the principles of quarks, although Gall Mann received the Nobel Prize for that discovery." It is not widely accepted that Ne'eman postulated anything that was not simply an antecedent to the quark theory. In other words, what you're saying – though sourced – implies something not widely agreed upon. My inference here is also partially drawn from the fact that you've effectively conceded a conflict of interest: "Ne'eman started to work on the idea on the early 1960s and I deeply believe (after hearing the all story from late Ne'eman himself-but it's off the record of course, no original research intend) that he was the first." I think the best solution is really just to leave the article as it is. This conflict is pointless. Ne'eman's work is duly noted and appropriately weighted. I really would advise that we leave it at that.

On another thing: please carefully read WP:VAND. The wording there might explain why I was so indignant when you labelled my edits vandalism. In doing so, you unambiguously asserted that what I was doing was nothing better than the work of the common graffiti artist who plasters articles with curse words. It was an insult, and you really should be more cautious and conservative when using the word – I note that you also applied the same term to Headbomb in the article history. Just something to think about.

Kind regards, —Anonymous Dissident^Talk 09:37, 16 September 2009 (UTC)

Agree with pretty much everything said right there. A shame it came to a block. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:06, 16 September 2009 (UTC)

I object to giving the specific date for Gell-Mann's, see [4] for the full reason. I won't revert since I may be the minority view here. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:16, 16 September 2009 (UTC)

Local SU(3) and rotations in color space

I just recognized that the following is written in the article:

"The physics of quantum chromodynamics is independent of which directions in three-dimensional color space are identified as blue, red, and green. SU(3)c color transformations correspond to "rotations" in color space (which, mathematically speaking, is a complex space). "

SU(3) is an eight dimensional group and therefore its not a three dimensional "color space". Am I right? 128.91.43.142 (talk) 23:38, 15 September 2009 (UTC)

No, SU(3) is not the color space, it is the symmetry group of the 3 dimensional color space. (TimothyRias (talk) 12:46, 21 September 2009 (UTC))

The color space is not 3-dimensinal. It is 2-dimensional. That mistake should be correct, if infact that's what's stated at the article. Dauto (talk) 17:49, 14 October 2009 (UTC)

The space on which SU(3)c acts is 3-dimesnional, and is conventionally called color space. It is as simple as that. (TimothyRias (talk) 18:14, 14 October 2009 (UTC))

Except that the space is in fact 2-dimensional. It is as simple as that. That comes about because the three color charges are not independent and satisfy the equation red+green+blue=zero. that constraint reduces the dimension of the space to two. A possibily more familiar example is the Gell-mann's flavor SU(3) (sometimes called the eight-fold way) where the space is spanned by only two quantum numbers: flavor isospin and flavour hypercharge. Dauto (talk) 18:50, 14 October 2009 (UTC)

No, red+green+blue are not actually zero, their antisymmetric tensor product is invariant under SU(3). To stay in the color analogy; red+green+blue=white but zero=black. The technical statement is very simple: "quarks transform in the fundamental representation of SU(3), which by definition (that is what the 3 in SU(3) stands for!) is a 3-dimensional representation."

About the eightfold way: flavour isospin is actually two quantum numbers (namely the charges of SU(2) total spin + azimuthal spin.) Together with hypercharge those are 3 charges. (TimothyRias (talk) 20:17, 14 October 2009 (UTC))

Let me parse your answer:

You say "No, red+green+blue are not actually zero, their antisymmetric tensor product is invariant under SU(3). To stay in the color analogy; red+green+blue=white but zero=black."

You are confusing the states of the triplet representation (which you correctly point out is the fundamental representation) with the color quantum numbers. You cannot take an antisymmetric tensor product of the colors because they are not tensors. The colors are aditive quantum numbers. You might represent them as vectors (in a 2-dimentional space). For instance: R=(1,0), G=(-1/2,SQRT(3)/2), and B=(-1/2,-SQRT(3)/2). Note that the three colors form the vertices of an equilateral triangle (in a 2-dimensional space) and their sum is zero R+G+B=(1-1/2-1/2,0+SQRT(3)/2-SQRT(3)/2)=(0,0)=zero. The quarks are members of a triplet and you might represent their three possible color states as |R>, |G>, and |B>. If you act on those states with the color operator (I'll call it COLOR) you get their color eigenvalues: COLOR|R>=R|R>, COLOR|G>=G|G>, and COLOR|B>=B|B>. Now you can (if you will) take the antisymmetric product of those states (Lets call it |A> for antisymmetric) and you get |A>=(1/3!)[|R>|G>|B> + |B>|R>|G> + |G>|B>|R> - |R>|B>|G> - |B>|G>|R> - |G>|R>|B>]. Now to apply the color operator on that state it is important to remember that the color operator will be given by COLOR = (COLOR X 1 X 1 + 1 X COLOR X 1 + 1 X 1 X COLOR). Applying that on the first term of the state |A> we get COLOR(|R>|G>|B>) = (COLOR X 1 X 1 + 1 X COLOR X 1 + 1 X 1 X COLOR) (|R>|G>|B>) = [(R|R>1|G>1|B>)+(1|R>G|G>1|B>)+(1|R>1|G>B|B>)]= (R+G+B)(|R>|G>|B>)=zero. The other five components of |A> will also vanish in a similar way and you finaly get COLOR|A>=zero. Your analogy "zero=black" means nothing to me.

You say "About the eightfold way: flavour isospin is actually two quantum numbers (namely the charges of SU(2) total spin + azimuthal spin.) Together with hypercharge those are 3 charges."

You are mixing apples with bananas here. The SU(2) total spin doesn't belong in that list. Dauto (talk) 23:42, 14 October 2009 (UTC)

I'd say go pick up a book on QCD and learn what your talking about, for now you are getting confused by the analogies used. Quarks transform in the fundamental representation of SU(3), the (internal) vectorspace (or bundle) is colloquially referred to as color space, and is three dimensional. Do to confinement lower energy observables need to transform as scalars under SU(3) (colloquially such an observable is called "white"). The only way to make such an observable from objects transforming in the 3-representation is by taking the anti-symmtetric tensor product of three of them. (Alternatively you can make an (SU(3) scalar from someting in the 3 and something in the 3-bar reperesentation. (TimothyRias (talk) 06:32, 15 October 2009 (UTC))

OK. I see what's going on. We are talking about two different things here. You are talking about the fact that it is possible to build a 3-component vector out of the three different states of the fundamental representation and build the other representations by applying all possible symmetry combinations to the product of those vectors (often times represented by Young tablaux). I'm talking about the rank of the algebra (Which is N-1 for the SU(N) algebra). I feel that is the appropiate measure for the dimension of the color space because it tells you how many components you actually need to identify the color states. The R, G , and B vectors are co-planar and span a 2-dimentional space. That's whay the pictures in the section quark#Strong interaction and color charge are all planar pictures. (They are pictures in 2-dimentions). Dauto (talk) 14:05, 15 October 2009 (UTC)

It's me who made the pictures. I hardly know anything about the group theory behind QCD, but the pictures also make sense if the color space is 3D: you just have to consider the color arrows as coming out of the screen by 36° to make the edges of a cube, and the anticolor arrows as going into the screen by the same amount. The only misleading thing would be that the three "whites" aren't the same ((1, 1, 1) for baryons, (−1, −1, −1) for antibaryons, and (0, 0, 0) for mesons). ___A. di M. 20:41, 27 October 2009 (UTC)

Unless somebody else objects I will fix the article by next weekend (I take Timothy's silence the last few days as a sign of consent, but please let me know if that's not the case)

I strongly object. You seem to know quite a bit about Lie groups/algebra's but not about noncommutativve gauge theory. Before making any changes, I'd suggest looking up a physics textbook on SU(N) gauge theories. Chapters 15 and 16 of Peskin and Schroeder will do for example. The three dimensions of color spaces is the dimension of the representation in which quarks transform. A common mistake made by people approaching the subject from a mathematical background is to assume that there is no physics in the choice of representation. This is blatantly false as is most pressingly expressed by the represntation of the Lorentzgroup determining the spin of a particle. (TimothyRias (talk) 09:02, 28 October 2009 (UTC))

(I'm currently somewhat internet deprived so my response may be somewhat slow.) (TimothyRias (talk) 09:03, 28 October 2009 (UTC))

I don't think my backgroung (or anybody else's) is very relevant to the discussion. But since you bring it up, I would like to point out that you are wrong to assume that my background is in the mathematics area. In fact, all my degrees are in physics and the last one is in phenomenology of grand unified models. I'm quite familiar with SU(N) gauge theories and I understand that the representations of these groups can be described as tensors of specific symmetries (anti-symmetric, symmetric, mixed symmetries etc...) and that the indices of those tensors may have values 1,2,...,N-1,N. My point is that the rank of the algebra is a better measure of the dimensionality of the space. Of course reasonable people can disagree about that, but hear me out. If the color space is tridimensional, how come the pictorial representations presented in this very article of the color space are bidimensional representations? There is nothing wrong about those representations and similar bidimensional pictures are often used elsewhere whenever the group SU(3) shows up. See for instance Eightfold Way (physics), baryons, and mesons. Those pictures are showing the hypercharge and the isospin which are the TWO quantun numbers necessary to describe those eigenstates. Either way something must be changed in the article because the tridimensionality of the space (as currently stated in the article) does not match the bidimentional pictures (and I would hate to see those go away) . Think about it, if SU(N) is N-dimensional, how come we never hear anybody talk about the group SU(1)? Dauto (talk) 18:40, 31 October 2009 (UTC)

Well, that is all nice OR, but in normal discussions of quarks, the quark fields are sections of a three dimensional vector bundle carrying the defining representation of SU(3). This number 3 subsequently shows up everywhere in your calculations. For example it is intimately related to quarks having charges in units of 1/3, etc. You can try to introduce a novel treatment of the subject all you want, but that goes against the policies of this project.

Also, Like anybody will tell you SU(N) is N² -1 dimensional. In particular SU(1) exists is zero dimensional. The reason nobody ever talks about it is because it is isomorphic to the trivial group of one element. Any field has an SU(1) symmetry and in fact infinitely many of them, it is just not interesting. (It's defining representation is 1-dimensional though.) (TimothyRias (talk) 09:47, 3 November 2009 (UTC))

Just because you are a little unfamiliar with what I'm talking about doesn't mean it is OR. Yes, you are right, the dimension of the algebra is N² -1 but its rank, which is what I'm talking about is N-1. Let me put things this way: The text talks about a tridimensional space but the pictures show a bidimensional space. Either one of them is wrong or they are both right but they are not refering to the same space. Either way the article is missleading at best and something should be changed. Dauto (talk) 15:52, 3 November 2009 (UTC)

What you're seeing is the 2D projection of the 3D space. Take a 3D orthogonal space, label the axis, red, green, and blue. Rotate it so the (1,1,1) vector faces you and this is what you are seeing. Baryons lives at (1,1,1), mesons at (0,0,0) and antibaryons at (−1,−1,−1). If the color space would be 2D, there would only be 2 colors. At least that's how I understand things. (Note that I also completely suck at group theory. I can't make any sense of the language used, groups, representations, etc...) Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:11, 3 November 2009 (UTC)

Sorry but those pictures are definitaly bidimensional. The baryons, anti-baryons and mesons are all color singlets. They are all in the same state as far as color eigenvalues are concerned. Dauto (talk) 21:54, 3 November 2009 (UTC)

No they're not. Baryon color wavefunction is:

$\Psi ={\frac {1}{\sqrt {6}}}\left(|rgb\rangle -|rbg\rangle -|grb\rangle +|rbg\rangle +|brg\rangle -|bgr\rangle \right)$

Meson color wavefunction is:

$\Psi ={\frac {1}{\sqrt {3}}}\left(|r{\bar {r}}\rangle +|g{\bar {g}}\rangle +|b{\bar {b}}\rangle \right)$

These are both singlets, but these are not the same singlets. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:38, 3 November 2009 (UTC)

It's the same thing. SU(N) has only one singlet representation. Dauto (talk) 23:25, 3 November 2009 (UTC)

And neither baryons nor mesons really live in that representation. Baryons (strictly speaking) live in the $3\otimes 3\otimes 3$ representation. This reducible representation has a 1-dimensional subrepresentation that is isomorphic to the singlet representation, and baryons must in fact belong to that invariant subspace. This means that in an effective theory for baryons they Baryon field can be treated as color singlets. Similarly, mesons live in (an invariant subspace of) the $3\otimes {\bar {3}}$ representation. (TimothyRias (talk) 10:18, 4 November 2009 (UTC))

You seem to be agreeing with me. Do you not agree that those pictures are bidimensional pictures? Dauto (talk) 15:48, 4 November 2009 (UTC)

How do you show three-dimensional pictures on a two-dimensional computer monitor? :-) ___A. di M. 16:06, 4 November 2009 (UTC)

Using perspective. That's a moot point though, since those pictures are bidimensional. Dauto (talk) 19:03, 4 November 2009 (UTC)

I don't think I'm agreeing with you. Although the pictures are abstractly drawn as 2d diagrams, they are meant to represent (base) "states" in $3\otimes 3\otimes 3$ and $3\otimes {\bar {3}}$ which are characterized by sets of 3d vectors. The picture mainly works by appealing to more common knowledge of normal colors. RGB space is 3-dimensional, yet everybody is used to selecting colors from a 2d palet (displaying different hues and saturation at at a fixed intensity). (TimothyRias (talk) 08:47, 5 November 2009 (UTC))

That's exactly why the color analogy is a good one. Despite RGB giving you 3 different parameters, color palets are bi-dimensional showing only hue and saturation because brightness is not part of the color (othewise you could change the color of an object just by shining some more light on it and that way increasing its brightness). Dauto (talk) 15:43, 5 November 2009 (UTC)

Black, gray and white are the same color then? :) This cute remark actually relates to our problem here. The color of any SU(3) state would be given by three quantum numbers. The quadratic Casimir/total charge labelling the representation (analog to the brightness) and to quantum numbers related to commuting generators of a maximal (2-dimensional) subtorus of SU(3). The total (color) charge of a quark is fixed (by the statement that they transform in the 3-representation). Leaving two more parameters to determine the direction of the color.

At the classical level (which is much more intuitive for lay readers), you could indeed say that the space of colors that a quark can have is only 2-dimensional (interestingly enough SU(3) orbits have 5 real-dimensions). At the same time it is equally valid to say that the total color space is 3-dimensional, the later is much more helpful in introducing SU(3) as "rotations in color space". (TimothyRias (talk) 16:24, 5 November 2009 (UTC))

I think you may be streching the analogy dangerously close to the breaking point when you compare the quadratic Casimir with brightness. The quadratic Casimir is not an aditive quantum number and that's why it does not belong in the list of color space quantum numbers. Again, you are mixing apples with bananas. Still, baryons and mesons are both color singlets and have the same quadratic Casimir (zero) and the pictures remain bidimensional. Dauto (talk) 20:53, 5 November 2009 (UTC)

Mesons and Baryons have all color quantum numbers equal. So by your logic, should the pictures be zero dimensional? You need three quantum numbers to determine the color state of a particle (The total charge plus two charges corresponding to commuting generators), just like you need 2 quantum numbers (total spin plus the projection of the spin in one direction) to determine the spin state of a particle. The numbers being additive is not the relevant condition here, it is whether the operators corresponding to these quantum numbers commute (and thus have a complete set of common eigenstates). (TimothyRias (talk) 09:06, 6 November 2009 (UTC))

An optical illusion. The square A is exactly the same shade of grey as square B.

PS: White and gray really are the same color. Just compare the squares labeled 'A' and 'B' in that picture from the optic illusion article. Two identical squares are perceived as either white or grey depending on the surrrounding brightness. Black on the other hand can be any color (Just try turning all the lights off after dark) due to a degeneracy of the tranformation between (R,G,B) and (Hue,Saturation, Brightness). (Similar to the degeneracy in the transformation between cartesian coordinates(x,y) and polar coordinates (r,theta) where (0,0) takes us into (0,theta) where theta remains indeterminate). Dauto (talk) 20:53, 5 November 2009 (UTC)

Cheng & Li: "Since T₃ and Y can be diagonalized simultaneously the states in an SU(3) irreducible representation must be labelled by two eigenvalues: T₃ and Y. A representation is then pictured as a two-dimensional figure on the T₃-Y plane, just as an SU(2) representation is a one-dimensional line." --Michael C. Price ^talk 13:31, 5 November 2009 (UTC)

Thank you Michael. I've been saying that for several days now, but I've been met with scepticism. Dauto (talk) 15:43, 5 November 2009 (UTC)

I think we have a serious point of miscommunication here. I think we are approaching the subject from completely different angles here. I take the approach come in theoretical particle physics introducing quarks as classical fields first that can be quantized with your favorite method (be it canonical or path-integral). From this point of view, the quark field is simply a three component field with the components labelled by the colors R, G, and B (or actually more commonly just 1, 2 and 3). The QCD lagrangian then happens to be invariant unders SU(3) rotations of these three fields. (Or I guess more accurately we construct a Lagrangian that contains all possible terms which are renormalizible and are invariant under SU(3) rotations of these fields (and are invariant under all the other symmetries we impose like Lorentz invariance). The free separate fields can also be view as section of a three dimensional vectorbundle. This number three (referred to as the number of colors) then consequently pops up all over in your calculations. For example, quark loops in Feynman diagrams contribute an additional factor 3 to take the number of colors in account. The color observable would simply be a vector valued operator with components (R,G,B) where R,G,B are simply the projections on the relevant directions in the bundle. The R, G, and B operators do not commute, and as such do not have (a complete set of) common eigenstates and eigenvalues.

You seem to be taking more common phenomenological approach of "observing" some quantum theory and trying to classify its states with suitable quantum numbers. For a SU(3) state this means specifying it representation (given by the quadratic Casimir) and two quantum numbers corresponding the commuting generators. You want to call this last set of commuting quantum numbers "the color" of a state. I guess analogous to calling the s_z azimuthal spin quantum number "the spin" of a state. Note that these only make sense if you've already specified the total spin and total color.

Both approaches are true. I know the first one is common in theoretically flavored books and I can imagine some phenomenological books taking the later approach. In popular books, I think the former is more common (although usually the exact meaning of what auhtors are saying is obscured in vagueness.) I prefer the former approach for a wikipedia article, since with its strong classical flavor it can more readily appeal to concepts know to a broad audience. The later approach has the merit of making the analogy to the additive color model more explicit, however only for people that are already somewhat familiar with the representation issues. It also obscures the very physical common statement that there a three quark colors. (TimothyRias (talk) 10:04, 6 November 2009 (UTC))

The dimensionality of SU(n) has three answers, which are all "correct":

1. n²-1 ; number of generators
2. n-1 ; rank (i.e. number of commuting generators)
3. n

They all have their uses. Just plugging one to the exclusion of the others is not helpful -- especially to beginners.--Michael C. Price ^talk 11:04, 6 November 2009 (UTC)

True. The current article mentions 1 and 3 in how they relate to quarks, namely as the number of gluons and the number of quark colors. Is there someway that we need to mention 2 in the article at all? That is, is their a sufficiently non-technical statement where this number pops up? (Note, that this an article about quarks, not about QCD or SU(3) the later would be more natural places to make more technical statements on the matter. (TimothyRias (talk) 11:14, 6 November 2009 (UTC))

Howabout, 8 gluons, 2 conserved charges, 3 colours?--Michael C. Price ^talk 11:34, 6 November 2009 (UTC)

Hmm... Aren't there 8 conserved charges? One for each generator of the group. At least that is the usually wisdom obtained from Noether's theorem. There are two quantum numbers needed to describe the quantum state of a single quark, that is the least technical I can currently think of. (TimothyRias (talk) 13:37, 6 November 2009 (UTC))

I mean the gauge invariant central charges, which are the same as the two eigenvalues you mention (I think). Not sure of the terminology. --Michael C. Price ^talk 14:10, 6 November 2009 (UTC)

But those charges are not gauge invariant nor are they central. It is just that they mutually commute. (TimothyRias (talk) 14:30, 6 November 2009 (UTC))

Yes, you're right; they're not central charges, not are they gauge invariant.--Michael C. Price ^talk 07:33, 8 November 2009 (UTC)

Thank you, Timothy, for that thoughtful post. It brought some clarity. I agree with everything you had to say. Turns out the article already mentions the (n-1) rank of the group. It does not mention it in words, but it does mention it in pictures. That's what those pictures I've been talking about represent. What bothers me is the missmatch of the text talking about a tridimensional space while the pictures are showing a bidimensional space. Dauto (talk) 13:06, 6 November 2009 (UTC)

Dauto, I actually have some trouble with literally interpreting the 2d pictures as representing the space of additive color quantum numbers. What the pictures need to portray is that we can combine three colored states to form a state that is invariant under color transformations. Finding that the additive color quantum numbers add to zero, however, is NOT enough to show that a state is invariant under SU(3). For example, as you showed above, the color quantum numbers for $|r\rangle \otimes |g\rangle \otimes |b\rangle$ vanish, but this state is not gauge invariant. That is only true for the completely antisymmetric combination of such states.

What is happening here, is that the additive color charges you mentioned actually correspond to the difference between the color charges. (Exactly what difference depends on a choice, but in the example you gave above the the color vector is given by (R-1/2G-1/2B,sqrt(3)/2(G-B)).) While, what we are looking for the establish gauge invariance is that the expectation value of the total color charge ("R^2 + G^2 + B^2") vanishes. (The vanishing of the additive charges only establishes that R=G=B.)

In order, for the diagrams to make any sense they must be interpreted representing a more abstract addition of states. This involves more than the apparent 2D nature of the diagrams. As such, one may say that the diagrams are somewhat misleading. But I think in this case "bad" diagrams are much better than no diagrams at all. (15:27, 9 November 2009 (UTC))

Yes, you are right that there is a lot under the rug so to speak. There are things that are not obvious from the diagrams such as the nature of gauge invariance and how that relates to the possible representations, as you pointed out. Still the best interpretation of the pictures are as pictures of the representation weights which is this 2-d space I'm talking about. Dauto (talk) 22:49, 11 November 2009 (UTC)

Mass section

In this section it states: "While gluons are inherently massless, they possess energy—more specifically, quantum chromodynamics binding energy (QCBE)—and it is this that contributes so greatly to the overall mass of the hadron (see mass in special relativity)." This is fine, except that the QCBE link redirects to the QCD article; after reading this, I saw no mention of QCBE. I'm not suggesting you amend the Quark article, or the QCD article, but maybe a new article QCBE should be written saying something about what is meant, for example defining QCBE. I understand that energy is equivalent to mass from E=mc squared. But I don't see how you get from the fact that gluons carry energy to the particular mass of the hadron; maybe that would be something to address in the new article? Puzl bustr (talk) 17:47, 9 November 2009 (UTC)

Sorry, should have read further before posting this question. I see that Constituent quark adresses this question, though from my POV the latter article could do with improvement. And the re-direction problem, with the non-definition of QCBE still stands. So perhaps the def. of QCBE could be a section within Constituent quark. I'll mention it on the talk page there.Puzl bustr (talk) 18:10, 9 November 2009 (UTC)

Size of a bare quark

Someone needs to address in the article the problem of various estimates for what the size of a bare quark might be. The section in the article should be titled "size estimates" Keraunos (talk) 09:01, 18 September 2009 (UTC)

Never mind, I see the question is already addressed in the section above called "a small question". Keraunos (talk) 09:09, 18 September 2009 (UTC)

It is clearly stated in the article that the quark and its fundamental particle cousins are point particles. —Anonymous Dissident^Talk 13:26, 18 September 2009 (UTC)

That is to say, unlike strings which have one dimension they have none/zero. Perhaps the best answer is that modern physics doesn't really extend the size concept below the planck length. 72.228.177.92 (talk) 01:09, 15 February 2010 (UTC)

No mention of mesons

Just a little thing, but in the intro it says quarks are only found in hadrons. How about mesons? 192.25.142.225 (talk) 18:03, 17 January 2010 (UTC)

Mesons are hadrons, as explained in the "Classification" section. ― A._di_M.^{2nd Dramaout} (formerly Army1987) 18:56, 17 January 2010 (UTC)

Contradiction?

The first paragraph states: "quarks are never found in isolation; they can only be found within hadrons".

The fourth paragraph states: "All six flavors of quark have since been observed in accelerator experiments".

If they were still within hadrons, how were they observed? Should the first paragraph read "quarks are never found naturally ..."? Or am I missing something?

Paul Magnussen (talk) 19:48, 15 September 2009 (UTC)

Yes, they were observed in hadrons with the exception of top quarks, which decay too quickly to form hadrons. The top quark isn't found in isolation either, it's just that it decays so quickly that it doesn't really have a chance to form hadrons (aka a bound state with other quarks). If you study the decay of hadrons, you can deduce all the properties of quarks (mass, quantum numbers, electric charge, and so on), including the top quark, but you never see them directly. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 20:13, 15 September 2009 (UTC)

I was about to post about that contradiction. It IS a contradiction following the natural logic of our language, it needs to be rephrased to suggest what you apparently mean to say, which is that they were observed _within hadrons_ in accelerator experiments. I'm going to be bold and do such edit right now. Pentalis (talk) 20:39, 15 September 2009 (UTC) (Updated signature)

That's the thing, we do not mean to say that. It's trickier than that because of the top quark, to say that all quarks have been observed within hadrons is very misleading at best, and untrue at worse. I'm not sure we should clarify this in the lead, and if we choose to, how to clarify it without going into a bunch of details. Perhaps a note could be used. What do others think?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:13, 16 September 2009 (UTC)

the phrase "they can only be found within hadrons" is incorrect as Headbomb explains above - i propose to remove it. Somewhere further in the article it may be explained that the reason quarks cannot be found in isolation is either because 1) the light quarks bind into hadrons 2) the heavy quarks decay before flying away too far to be considered "isolated". By the way isnt it funny how many particle physics statements provoke the ancient argument "if you cannot see it how can you be sure it exists". Kotika98 (talk) 06:05, 16 November 2009 (UTC)

Yet not surprising as we move into territory where "see" (see? what?! with photons?!?), in its original sense, becomes inapplicable, and we are forced move to other forms of evidence. Wwheaton (talk) 15:53, 16 November 2009 (UTC)

Seems perfect as is, i.e. a la Empereur Naturale. 72.228.150.44 (talk) 14:35, 9 January 2010 (UTC)

Natural language must ultimately make sense as must physical theories. Usually this is often really doof stuff like a failure to stipulate the exact semantics of "observed". This is especially irritating to intelligent and informed but non-specialist readers when there is an aggressive assertion of non-sense such as that a thing that has been stated to be in principle unobservable has in fact been observed and oh by the way I can't explicate this because of an extra-special case of a very special kind of one these unobservable things which if it weren't for that your simple minded insistence on the sense of natural language might make sense. 72.228.177.92 (talk) 01:03, 15 February 2010 (UTC)

Could the evidence of quarks developed more in full? I can't understand from what's explained if there is any direct evidence for the existence of quarks or if it's existence is just deduced from the decay properties of hadrons. It kind of seems that we do have evidence that hadrons are non-elementary, but that the exact properties of this sub-hadron particles have been deduced. As a reader I would appreciate an explanation as simple as possible of how direct is our knowledge of this beasts and what kind of predictions have validated the theory. Actually, a section labeled "Evidence of Quarks" would be lovely. Futureme67 (talk) 15:27, 18 July 2010 (UTC)

It depends on how "direct" you want the evidence to be (after all they can't be seen by the naked eye, so it has to be "indirect" to some extent). I would consider deep inelastic scattering to be somewhat direct, though. A. di M. (formerly Army1987) (talk) 15:53, 18 July 2010 (UTC)

Thank-you, reading deep inelastic scattering makes it much clearer. May I suggest changing the wording of "and there was little evidence for their physical existence until 1968." to "and there was little evidence for their physical existence until 1968 when it was proved using deep inelastic scattering" ? Futureme67 (talk) 16:07, 18 July 2010 (UTC)

Well in the history section, we do write "In 1968, deep inelastic scattering experiments at the Stanford Linear Accelerator Center (SLAC) showed that the proton contained much smaller, point-like objects and was therefore not an elementary particle.". This seems sufficient to me. Headbomb {talk / contribs / physics / books} 15:11, 19 July 2010 (UTC)

However, we do mention Fermilab alongside the top quark in the lead, so maybe we should also mention SLAC in the lead. Headbomb {talk / contribs / physics / books} 15:14, 19 July 2010 (UTC)

popular culture

should we (wikipedia users) include a popular culture section to the quark article? i wud like to start 1, 76.70.86.63 (talk) 21:51, 27 January 2010 (UTC)

No. Such a thing serves no purpose. -RadicalOne•^{Contact Me}•_{Chase My Tail} 21:53, 27 January 2010 (UTC)

I agree; no need for that here. Let's keep this an article about the subatomic physics topic. At the front of this article is a link to Quark (disambiguation), which contains a list of other uses of the word quark, including the pop culture references. CosineKitty (talk) 23:02, 27 January 2010 (UTC)

• Please no. —Anonymous Dissident^Talk 20:59, 16 February 2010 (UTC)

Harari's quark model

See doi:10.1016/0370-2693(75)90072-6. I don't know the relevance of this yet; I've reverted it on top quark and bottom quark as well (for now at least), since the claim of precedence seems to be contradicted by Kobayashi & Maskawa's postulation of the third generation of quarks in their 1973 article on CP violation. Don't have access to the article right now, so ... yeah. But this article could contain something historically relevant nonetheless, even if the claim of predecence is itself bunk. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 00:04, 22 February 2010 (UTC)

Last year when trying to get to the bottom of this top/bottom vs. truth/beauty business, I came a cross some references to that article, but couldn't find a digital version. It is a good candidate for the first recorded use of the names "top" and "bottom". Gell-Mann in a 1975 article, names it "for example" as a prior article to use this name. The main issue here though is that primary sources are not very good for supporting the claim that somebody or something was the first of something. Any claim that X was the first to Y, should really be accompanied by a references to a RS saying so. TimothyRias (talk) 09:20, 22 February 2010 (UTC)

H. Harari actually COINED the names of the "top" and "bottom" quarks. Harari was the first to propose a model of six quarks and six leptons, naming the two new quarks “top” and “bottom” (names presently accepted by all), and predicting the existence of six leptons. In August 1975, at the Stanford International Particle Physics conference he presented, for the first time ever, the full synthesis accepted today as “the standard model” of six quarks and six leptons. Its seems that the authors of this page arent from the field of HEP. Barak90 (talk) 10:18, 22 February 2010 (UTC)

Well, Harari was not the first to propose a six quark model. That honor goes to KM in 1972. (with some caveat about them actually talking about quarks.) He is also preceded by a six quark model published by Barnett published in January of 1975. The only fact that can be really pinned on Harari is coining of the terms "top" and "bottom" (for which I have finally found a source, yeah.) You might want to get your facts straight before making other people out for ignorant.TimothyRias (talk) 11:24, 22 February 2010 (UTC)

Timothy Rias, I agree with your comments! However, In August 1975, at the Stanford International Particle Physics conference Harari presented, for the first time ever, the full synthesis accepted today as “the standard model” of six quarks and six leptons. I can show you the SLAC conference. Nevertheless, your editing regarding the names of top and bottom are totally acceptable!!! thanks Barak90 (talk) 15:14, 22 February 2010 (UTC)

I note that this might also make a good addition to Standard Model, although exactly how has to be carefully considered. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:55, 22 February 2010 (UTC)

Quark name

"Three quarks for Muster Mark" seems to be the common ground of all explanations for the name of these particles. However in German "Quark" is curd (see also Quark (cheese)) and is known to every child especially with the sentence "Quark macht stark" - "Curd makes powerful". Because of this strong association for native German speakers (it is even almost the same spelling) it is no wonder that in the German version of this article a different explanation for "Three quarks for Muster Mark" is cited: "Joyce hatte das Wort wiederum auf der Durchreise auf dem Bauernmarkt in Freiburg im Breisgau gehört, als Marktfrauen ihre Milchprodukte anboten." - "Joyce had heard the word during a journey through at the farmer's market of Freiburg im Breisgau, when market-women offered their milk products." This is referenced with the source: Harald Fritzsch: Das absolut unveränderliche. Die letzten Rätsel der Physik 2007, ISBN 978-3492249850, S. 99. As this is quite different from Gell-Mann's explanation for "Three quarks for Muster Mark" quoted in the English version ("Three quarts for Mister Mark") I'd be very much interested in bringing these explanations into coherence. Arnomane (talk) 22:54, 1 April 2010 (UTC)

Is there any evidence that Gell-Mann was aware of that? Note that we never say where Joyce took that term except through Gell-Mann's words quoted as such, where he clearly says that he kind-of made up the etymology so to have the pronunciation he liked. (Discussions of where Joyce actually took that word would belong to Finnegans Wake if anywhere.) ― ___A._di_M. (formerly Army1987) 09:55, 2 April 2010 (UTC)

Well I don't want to start an in-depth analysis of Finnegans Wake within this article but the etymology of the term "Quark" for Partons certainly belongs here. It would be strange to leave out any mention of "Quark - Curd" if Joyce indeed was influenced by the German word (which I can't say, as I don't have the cited book of a physicist nor am I a familar with Joyce literature) even if Gell-Mann wasn't aware. In order to clarify this matter I also placed a note on de:Diskussion:Quark_(Physik)#Namensherkunft.

My deeper motivation for this is that it shouldn't depend from your mother language, what you consider "the trouth". The most famous example for this is the question who invented the telephone. Was it Johann Philipp Reis or Alexander Graham Bell or someone else... For many centuries you could read completly different stories in different national encyclopedias. Today this is mostly settled with Reis having coined the word telephone and having done the first electrical speach transmission and Bell having invented/patented the first practical working telephone. Arnomane (talk) 13:29, 2 April 2010 (UTC)

Antonio Meucci invented the telephone, of course. (You can guess at my nationality from my signature.) :-) ― ___A._di_M. (formerly Army1987) 15:12, 2 April 2010 (UTC)

It must be confusing for young children in Germany to be told that matter is made out of three different kinds of cream cheese. —Preceding unsigned comment added by 192.168.1.99 (talk • contribs)

History omits names of Nobel Laureates

There are a lot of names mentioned in the History section and while the experiments are mentioned, the names of the physicists and the fact that they won the Nobel Prize for it seem to be missing.

From nobelprize.org:

The Nobel Prize in Physics 1990 was awarded jointly to Jerome I. Friedman, Henry W. Kendall and Richard E. Taylor "for their pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics".

--John I am art (talk) 22:55, 4 September 2010 (UTC)

Excitement

What about Excited quarks and the Glashow-Iliopoulos-Maiani mechanism? And LHC Quark excitement? --Pawyilee (talk) 12:09, 15 September 2010 (UTC)

What about it? Headbomb {talk / contribs / physics / books} 12:20, 15 September 2010 (UTC)

Recent addition by Nergaal

I just reverted a recent addition from Nergaal:

Quarks are fundamental particles because they lack any further substructures. If such substructures were to exist, the particles would exhibit excited states. However, as of September 2010, scientist have excluded such states below 1.26 TeV/c² at a confidence level of 95%.

I'm not fundamentally opposed to including this, but I do think the material should be considered here first. We have a feature article, and we'd be using preprints to support non-trivial claims. Do the searches on substructure warrant a mention? If so, should we explain the basic physics of the searches? Etc... Headbomb {talk / contribs / physics / books} 18:19, 17 September 2010 (UTC)

Radius??

The article on Protons discusses "charge radius" Is there such a concept for quarks, and if so, could that be added, be it charge radius, or radius with respect to other measurable inherent property other than charge, how much smaller would the "rms" radius be than a protons? Or not defined, or poorly understood? If known or even estimate known (or even tentative theory about such radius), then worth including in this article imo 04:43, 16 October 2010 (UTC)

Fundamental particles (leptons and quarks) have no charge radius, because their charge (bare charge) goes to infinity at radius zero. At least according to QED theory, only vacuum polarization keeps their measured charge from being infinity, but as you get close them, their charge keeps increasing without bound, like the gravity of a black hole. It's a singularity, but one which is hidden by vacuum polarization. With compound objects like protons, that isn't true-- the charge-density at the center of a proton really does have a non-infinite value, so it's not like a black hole. In that case, a charge radius makes more physical sense. SBHarris 04:59, 16 October 2010 (UTC)

I thought there were only 3 Fundamental forces?

Stupid question, but weren't the weak nuclear force and the electromagnetic force determined to be part of the same force (the electro-weak force) due to the discovery of the W and Z bosons at CERN in 1985? Dr. Entropy (talk) 06:37, 19 December 2010 (UTC)

Not really, but I would dare to say this question will only be completely resolved once the mechanism of electroweak symmetry breaking is discovered and understood - for example the higgs boson(s). In the Standard Model at least, the electro-weak force is not a completely unified thing, it is the sum of the weak isospin force (which also encompasses the W bosons) and the weak hypercharge force. It turned out that what we know as photon and Z boson are both a mixture of a part of the weak isospin force and the weak hypercharge force, the degree of this mixing being governed by the weak mixing angle. It it therefore misleading (unfortunately, it is oftentimes done nevertheless) to talk of the electroweak force as a unified force. Aknochel (talk) 11:18, 8 February 2011 (UTC)

I agree 100%. The electroweak interaction is NOT a unified interaction. Dauto (talk) 16:21, 8 February 2011 (UTC)

Existence of quarks no longer in dispute

I have reverted an edit by Maplelanefarm re. the existence of quarks. To the point that it needs to be mentioned in the lead, this is no longer in dispute. As with atoms about a century ago, quarks are essentially universally accepted as real, even though not directly observed. The deep electron scattering results from SLAC (since about 1970) and the remarkable successes of the Standard model have essentially laid existence questions to rest. The reality of quarks (as of atoms) was widely doubted in the 1960's, and this deserves passing mention (IMHO) deeper in the article. Wwheaton (talk) 14:57, 5 February 2011 (UTC)

Origin of the name 'quark'

The truthiness of Murray Gell-Mann's version may be in dispute.

According to the book "The Infinity Puzzle" by Frank Close (Oxford University Press 2011), the following occurred:

First, Murray Gell-Mann was unconvinced of the physical reality of quarks until very late in the game and considered them quirks of the description:

"In 1965, Dick Dalitz took the idea seriously enough to imagine, like Zweig, that quarks build hadrons by rotating and orbiting around one another, following the same rules as electrons in atoms, or protons and neutrons within atomic nuclei. When he spoke about these ideas at an international conference in Berkeley in 1966, Gell-Mann stood up and walked out (...) By the summer of 1968 I [Frank Close] had almost completed my first calculations in the model and learned that Gell-Mann himself would give two talks about particle physics at the Rutherford Laboratory, some 20 miles south of Oxford. The opportunity was too good to miss: Gell-Mann surely could verify that quarks are real. At the end of the first talk I asked him, His reply was unequivocal: for him quarks were a mnemonic and a "convenient way of keeping track of the mathematical group theory". This denial of "concrete quarks" further disillusioned me, its impact so dramatic that it has stayed with me ever since. So I was surprised when years later, by which time quarks had been established as physical entities capable of scattering electrons and other particles, Gell-Mann seemed to be singing a somewhat different tune." [pages 228,229]

In 1963 according the Frank Close, the following happened:

"In March 1963 Gell-Mann gave a talk at Columbia University about his new SU3 theory. A couple of weeks earlier another theorist, Gian Carlo Wick, had given an introductory seminar about SU3; upon hearing it, Robert Serber realised that in addition to families of eight and ten, which had already been discovered, there should be a basic family of three (as in SU "three") and, moreover, the octets and tens should be built up as composed of groups of these more basic entities. As Server later recalled: "The suggestion was immediate; the [hadrons] were not elementary but were mad of [what we now call] quarks." A forthnight later, Gell-Mann was in town. During lunch at the Faculty Club, Serber explained the idea to him. Gell-Mann asked what the electric charge of the basic trio is. Serber had not looked into this, so Gell-Mann figured it out on a table napkin. The answer turned out to be 2/3 or -1/3 fractions of a proton's charge, which was an "appalling result", as no such charges had ever been seen. Gell-Mann mentioned this in the colloquium, and said that such things would be a "strange quirk of nature". Server remarked later: "Quirk was jokingly transformed into quark." [page 225]

This event is referenced by Frank Close as from "R.Serber, with R.P. Crease, Peace and War, Columbia University Press p.199."

Frank Close also gives "Gell-Mann's version is at www.webofstories.com/play/10658" — Preceding unsigned comment added by 178.254.101.116 (talk) 15:19, 9 September 2012 (UTC)

Size?

Is there any experimental or theoretical estimates of the size (diameter) of quarks? Or are they still treated like point-size (zero diameter) particles? — Loadmaster (talk) 23:03, 9 March 2011 (UTC)

The theory assumes them to be point-sized; I don't know the current experimental upper bound on their size right now (10×10⁻²¹ metres-ish, I'd guess?), but probably the Review of Particle Physics gives it. --A. di M. (talk) 23:12, 9 March 2011 (UTC)

“charm, strange” or “strange, charm”?

[5]. In the original version, they were sorted within each generation by decreasing electric charge, now they're sorted by increasing mass. I prefer the former, but before reverting I'd like to hear more opinions. ― A. di M.​_plé​^dréachtaí 10:37, 24 July 2011 (UTC)

Sorting by mass seems more conventional. (especially since this is also the historic order in which they were discovered. Note that this would also mean saying "bottom and top" rather than "top and bottom". I don't have a big preference either way though.TR 16:08, 24 July 2011 (UTC)

Good catch wrt top and bottom. I'll swap them too, while waiting for more opinions. ― A. di M.​_plé​^dréachtaí 16:41, 24 July 2011 (UTC)

Up antiquark or anti-up quark?

I notice some placed say up antiquark while others say anti-up quark. In my opinion, anti-up quark is much more clear. Either way, we should probably pick one way to state anti-quarks and stick with it. D O N D E groovily Talk to me 18:54, 13 December 2011 (UTC)

Reality of Quarks

I recently placed the following in the article: It should be kept in mind that, technically speaking, quarks are not real objects. When calculating quantities in QCD using the method known as perturbation theory, one obtains lines in the diagrams that are very similar to the electron lines in Quantum Electrodynamics(QED). From this analogy one speaks of quarks. However, unlike QED, these lines do not correspond to an actual particle in the spectrum of the theory. That is QCD does not predict the existence of a particle like the quark, it is simply that a specific method of calculation (perturbation theory) produces terms which are intuitively easier to interpret as coming from fermion particles. However these quarks do not exist in spite of how useful it is to think about them.

Could somebody tell me what is incorrect about this? There is no quark state in the QCD spectrum, all states are colorless. Even more strongly, in QCD_2 (2D QCD using constructive field theory language), there is no pole in the fermion bilinear, which would imply such a state. Also quarks are renormalisation group variant and gauge variant, hence they are not real quantities. 2001:770:10:300:0:0:86E2:5103 (talk) 08:57, 11 June 2012 (UTC) username

What you say is only true at low energies/temperatures. At high temperatures, QCD does predict independent (colored) particle quark states. The fact that there are no free quark states at low energies, is already discussed at quite some length in the article.TR 09:43, 11 June 2012 (UTC)

Thank you for your response. You are of course correct, I should have written my paragraph in a different way. What I wanted to explain is that a proton, for example, is not "made of quarks", since in that

phase of the theory there are no quarks and one cannot really say the proton is a bound state of color states. (I think Nakanishi's "Covariant Operator formalism of Gauge theories" has something on this.)

Rather the proton is just a state in the QCD Hilbert, which doesn't result from different states being bound together.2001:770:10:300:0:0:86E2:5103 (talk) 12:57, 11 June 2012 (UTC) username

That is a point of semantics, which is dodgy anyhow in the quantum regime.TR 13:23, 11 June 2012 (UTC)

A bit clearer: the whole concept of a bound state only makes sense in terms of perturbation theory (the thing you were trying to say is not "real"). In a non-perturbative sense there is no such thing as a bound state, there are just states. (In a strict sense, this is also true for atoms. Perturbatively they are well described as a bound state of the nucleus with some electrons, but in a strict sense they are simply the lowest energy states.) Nonetheless, there some very concrete ways in which hadrons may be thought of as a collection of quarks. (For example, when discussing scattering in terms of parton functions, or in terms of determining decay through the weak interaction.

So, it is rather questionable to say that quarks are less real than leptons. And for a general audience, I think it is more confusing to try to explain in what sense they are or are not real.TR 13:48, 11 June 2012 (UTC)

I don't agree with the above, but perhaps I'm wrong. If I take, for example, a positronium state, that state is always a superposition of electron-positron two particle states and the observables associated to each particle individually have well defined expectation values. This makes sense nonperturbatively as well, even rigorously (for example two-particle bound states have been found constructively in scalar field theories in lower dimensions, by Glimm and Jaffe). In fact I would have thought that bound states only really make sense in QFT non-perturbatively via the Bethe-Salpeter Kernel, perturbatively you don't really see the properties of bound states. Other states which we call bound states are always some subspace (with the relevant quantum numbers) of the appropriate n-particle states. For quarks this is not the case, as there are no single quark states. Rather a proton, or a meson are themselves the single particle states and single quark observables are not well defined on these states (as they are gauge variant). At high temperatures the Hilbert space changes (moves to a different representation) and one does get free states with a color charge. However there is no proton in this new state space. Hence a proton is not made of quarks, but positronium is made of an electron and a positron.2001:770:10:300:0:0:86E2:5103 (talk) 07:59, 12 June 2012 (UTC)

(The notion of an n-particle state, only makes sense perturbatively, since it is always the n-particle state of the free field theory, instead of the full interacting theory.)

Actually, from what is known from lattice QCD, the phase transition from the quark-gluon plasma phase, to the hadronic phase is characterized by the formation of bound quark states. (Which do make sense in the regime of the phase transition.)

Anyhow, whether you agree with me or not, my point here stands that arguing the "reality" of various quantum states is rather subtle and not suitable for an article aimed at a general audience. The article already makes the point that there are no free quark states at low temperatures, which in effect is all you have been saying.TR 09:44, 12 June 2012 (UTC)

Yes, agreed, it's too much for an article such as this. Thank you very much for the discussion 2001:770:10:300:0:0:86E2:5103 (talk) 13:13, 12 June 2012 (UTC)

“top quark”

'top quark' has a mass comparable to that of a gold 'nucleus' as stated by physicists or to that of a gold 'atom' as stated by wiki author Headbomb? — Preceding unsigned comment added by Uscbino (talk • contribs) 23:37, 6 August 2013 (UTC)

In this context it makes no difference, since we're not concerned with exact values, and the mass of the electrons in a gold atom is negligible. Interestingly, though, the Top quark article says the mass is about the same as a tungsten atom, not gold, which seems to agree with the stated value (by my calculations, 173 GeV is about 186 amu). Perhaps this article should be reworded? Unfortunately the link is dead, so I can't check the source of the "gold" comparison. Never mind, I found the reference (and fixed the link). The press release does indeed say "about the mass of a gold nucleus" - BUT that information is out of date, as it refers to the mass of 178GeV reported at the time (2004) rather than the currently accepted value of 173GeV. (And even then, iridium would have been a more accurate comparison - but I guess they thought the general public would be more likely to have heard of gold...) By the way, that comparison appears twice in this article. Not sure if the reference under History should stay, with the clarification that this is what was believed at the time, but the one under Mass would seem to be just plain wrong. 78.146.214.35 (talk) 01:23, 3 November 2013 (UTC)

Up to down quark charge value change considerations

For an up quark with a +2/3 charge to change top a down quark with a -1/3 charge there has to be a change of minus 1 unit of charge. However there is no 1 unit of charge change value permitted for the properties of the 6 speculated quark entities. The change of the charge of the top quark to the top antiquark is from +2/3 to -2/3 or - 4/3 units of charge and the change of the charge of the bottom quark to the bottom antiquark is from -1/3 to +1/3 or a change of = 2/3 units. So it is not understandable as to how a unit change of a proton to a neutron can be accomplished by this theory.WFPM (talk) 19:44, 2 November 2013 (UTC)

That's because top quarks don't decay into top antiquarks (and vice-versa). If you want to change a proton (uud) to a neutron (udd), you change one up (+2/3) to one down quark (-1/3) by the emission of a W⁺ boson. See beta decay for more. Headbomb {talk / contribs / physics / books} 19:50, 2 November 2013 (UTC)

Thank you! So we must be playing with accumulated charge values around here and the W+ must be some kind of magic wand that subtracts a 1+ charge from an u quark and makes it a d quark, and the next question that comes is why it didn't have a +1 charge in the first place.WFPM (talk) 19:15, 3 November 2013 (UTC)

The "magic wand" is simply the conservation of electrical charge, although I'm not quite sure what you mean by "accumulated charge" and "why it didn't have a +1 charge in the first place". Headbomb {talk / contribs / physics / books} 02:40, 4 November 2013 (UTC)

Well if the +2/3 charge of the U can be converted into the -1/3 of the d by the emission of a +1, then we must be dealing with 3 separate entities whose individual charges can be "accumulated" and integrated into a "net sum". And of course the individual charges on the proton (and neutron} must be considered as being a "net sum" of the individual quark charges. So now the amount of charge of a particle has become a variable increment of some smaller than unit value. like maybe +-1/3?. So much for Gell Mann"s algebraic calculations.WFPM (talk) 20:42, 5 November 2013 (UTC However, if there is a possibility of the division of the electron (or the positron) into a number of smaller unit charge values, one would think that some evidence of such an occurrence would have cropped up in experiments related to the determination of the e/m value of these particles such as is carried in the Milliken oil drop e/m determination experiments.WFPM (talk) 04:04, 7 November 2013 (UTC)

Magnetic moment

What data are available about magnetic moment of quarks?--193.231.19.53 (talk) 17:10, 5 December 2013 (UTC)

In general, try the WP:REFDESK for questions like these. Or google. Headbomb {talk / contribs / physics / books} 17:16, 5 December 2013 (UTC)

I thought that someone working in particle physics, such as user Headbomb if I understand right, would know what data are available concerning this topic.--193.231.19.53 (talk) 11:08, 10 December 2013 (UTC)

It seems that there is a lack of determined data regarding the magnetic moment of quarks, as pointed out by googling [6].--193.231.19.53 (talk) 11:14, 10 December 2013 (UTC)

Are quarks observable or not?

Greetings, physicists! I am wondering about the seeming contradiction between two claims in the lead paragraph of this article. First we have "quarks are never directly observed or found in isolation" and then, later on, "All six flavors of quark have since been observed in accelerator experiments". This confuses me, and I wonder if there's some way it could be clarified or if maybe I'm just missing something? Thanks for your attention.— alf laylah wa laylah (talk) 04:12, 30 January 2014 (UTC)

Perhaps if we change the second one into "All six flavors of quark have since been indirectly observed in accelerator experiments"? - DVdm (talk) 08:33, 30 January 2014 (UTC)

Why was you confused? Leptons and photons can be isolated, but quarks and gluons cannot due to color confinement – it’s the main difference between those elementary particle that do not experience the strong force and those that do. But you also can’t isolate electron pair from an atomic matter, does it make the pair unobservable? Or does it make the pole of a magnet unobservable? Incnis Mrsi (talk) 09:35, 30 January 2014 (UTC)

No, look, I understand that elementary particles can be said to have been "observed" when predictions made from the assumption of their existence has been observed. That's what you're talking about here, right? Like what Thomson did with electrons. My only question is that for someone who doesn't know much about science it's very jarring to read that they can't be observed in isolation and then a few sentences later that they've all been observed. I'm not suggesting a change nor criticizing the article, which is excellent. I'm just pointing out something that confused me in case someone here wanted to know and possibly do something about it. I don't even know enough to assert that something should be done, but I do know that it can be hard for people immersed in technical subjects to see how their work reads to others. @DVdm, so that's what the second sentence means? Indirect observation? That's what I figured, but it's so hard to be sure.— alf laylah wa laylah (talk) 14:50, 30 January 2014 (UTC)

Indirect observation of quarks by direct observation of decay products, predicted by (or compatible with) the theory. We could even add a source like this

Wouldn't do much harm I guess. DVdm (talk) 15:50, 30 January 2014 (UTC)

It would have helped me. After some thought I figured out that you all must be using "observed" in that sense, but I'm fairly familiar with science, though not physics, and it still jarred me. I think someone who doesn't understand all the ways the word "observed" is used in science might have been more confused. Anyway, thanks for listening, and like I said, I don't know enough about it to suggest an edit.— alf laylah wa laylah (talk) 16:01, 30 January 2014 (UTC)

I have reworded that second sentence to "Accelerator experiments have provided evidence for all six flavors. The top quark was the last to be discovered at Fermilab in 1995."

It was a very good question and suggestion. Thanks for spotting it! - DVdm (talk) 18:33, 30 January 2014 (UTC)

Quark mass diagram has a shading problem

A problem in https://en.wikipedia.org/wiki/File:Quark_masses_as_balls.svg :

The up quark is shown as a light, unshaded disk, which (wrongly) makes it look larger (more massive) than the down quark. Shading the up quark to match the others would fix this problem. Lightening the shading of the top quark would help, too — its wide, nearly-black border makes it a poor background for the other quarks, which themselves have nearly-black borders. — Preceding unsigned comment added by Eric Drexler (talk • contribs) 22:47, 16 April 2014 (UTC)

Best ordering for list of flavors?

From the article:
"There are six types of quarks, known as flavors: up, down, strange, charm, bottom, and top."
Wouldn't it be more orderly to list them as up, down, charm, strange, top, bottom (i.e. alternating up-type with down-type)? Naramatac (talk) 23:22, 25 December 2013 (UTC)

It has always been customary to list them in increasing mass. Cuzkatzimhut (talk) 18:58, 12 May 2014 (UTC)

I don't know what's customary. To me, as a layman, "up, down, charm, strange, top, bottom" seems the most logical and intuitive ordering. It reflects the presentation in the table of elementary particles in the standard model. But in any case, whatever sequence is chosen must be applied consistently throughout the article. The article now seems to vary with no logic between several possible sequences of the six flavors.zadignose (talk) 05:10, 23 July 2014 (UTC)

Change infobox to mention flavors

Hey the infobox show the line: Types 6 (up, down, strange, charm, bottom, and top) Could it be changed to Flavors with a link to the article?186.231.123.122 (talk) 23:14, 9 April 2014 (UTC)

Agreed. Quarks come in two types (up-type and down-type) and six flavors. Due to a limitation of how "Infobox Particle" is designed, the current infobox misleadingly says there are six types. 75.163.161.124 (talk) 17:21, 20 September 2014 (UTC)

Describing the "other charges" of antiquarks

The article says that in antiquarks, "the electric charge and other charges have the opposite sign."

Am I correct in thinking that "other charges" refers only to the color charge?

Is it really correct to say that, for example, in an antiblue quark, the color charge has "the opposite sign" as in a blue quark? That would be equivalent to saying that a blue quark has +1 blueness and an antiblue quark has -1 blueness. Does any physicist actually think in these terms? If not, we should come up with a better way to describe antiquarks, than saying that the "other charges have the opposite sign." GPS Pilot (talk) 17:39, 20 September 2014 (UTC)

Other charges include flavour, color, isospin, weak isospin, and a couple of others. As for the question of whether or not physicists think in terms of "bluness", I suppose it's up to the individual physicist, but there's no difference between say, thinking a strange quark as a strangeness of S = -1 and the strange antiquark a strangeness of S = +1, and what you just mentioned above. Headbomb {talk / contribs / physics / books} 01:47, 22 September 2014 (UTC)

Quark magnetic moments

I've been poking at the article Neutron magnetic moment of late and so have been contemplating the magnetic moments of quarks. I gather the topic is not so easy - as a Dirac particle, one definition of magnetic moment is specified by theory, but then there is the effective magnetic moment after all the gluons and virtual particles are taken into account. The issue may be tied in with the effective mass of a quark, since the Dirac particle expression for magnetic moment has the mass parameter in the denominator - should one use the "bare" mass, or effective mass (1/3 mass of nucleon). Anyways, I noted that this article does not discuss the quark magnetic moments - no suitable reference comes to mind. The topic is under-appreciated IMO, insofar as quarks are concerned. It looks to me like the issue of magnetic moments of nucleons/quarks has, at times, played key roles in the development of the quark model. Bdushaw (talk) 21:18, 16 May 2015 (UTC)

Why do the physicists invent precarious particles, e.g. quarks, gluons et cetera, to define the structures of the real particles and atomic nuclei?

The structures of particles and atomic nuclei can be explained with only well-known particles. In fact myons, charged pions and kaons are the substructured particles of nuclei and proton as well as heavier particles. Myons, pions and kaons for their part are products of highly energetic interactions by electrons and positrons. Electrons and positrons are interacting in definite mumerical proportions and in each case specific energy. So you can find to every particle or nucleus an exact substructure and elementary structure. Particle qualities, e.g. strangeness, are the result of similar substructures. The causes of all kinds of strength (from the strong nuclear power to gravitational load) are the correlations between electron and positron or the substructured particles, at last only between electron and positron. HG.Hil,2003:4F:2D0E:9B60:3447:637E:69C5:24A6 (talk) 06:49, 15 May 2015 (UTC)

Same reason why chemists invent 'precarious' particles, e.g. atoms, electrons, et cetera, to define the structures of the real objects and molecules. It works and corresponds to an underlying physical reality. Headbomb {talk / contribs / physics / books} 12:17, 15 May 2015 (UTC)

I see this discussion and it must be said that there is at least a difference between atoms and electrons and quarks. The existence of atoms and electrons is inferred un-ambiguously on experimental macroscopic evidence (stoichiometry). Not the same can be said about quarks, their experimental basis is very ambiguous and they have not been detected in free state.--5.2.202.50 (talk) 18:11, 9 June 2015 (UTC)

Measurement of mass of quarks

Can the mass of quarks be measured if they cannot be observed as free particles? Or it is just calculated? The details are missing.--193.231.9.3 (talk) 14:30, 8 May 2014 (UTC)

It is estimated on the basis of measurement, like several of the fundamental parameters of QCD, a highly technical issue out of place in this general article. The section on mass already indicates multiple definitions. Cuzkatzimhut (talk) 19:01, 12 May 2014 (UTC)

What kind of measurement? A few details would be useful.--85.121.32.1 (talk) 13:44, 9 March 2016 (UTC)

André Petermann

I have reverted this addition from an IP [7], more as a precaution than as an actual disagreement with this. If André Petermann did propose quarks, this would be a major historical oversight, which should indeed be corrected. However, we must evaluate these claims against the strength of the references provided.

The supporting references are arXiv:1412.8681 (non-peer reviewed, but Petrov can certainly be considered an expert/legit historian here) and doi:10.1016/0029-5582(65)90348-2 (original paper by Petermann). I've read the arxiv paper, and there does seems to be some merit to the idea that Petermann independently proposed quarks, but little (direct) evidence is presented for it. Petrov cites the Petermann paper directly, but does not highlight specific passages from it. So we must check the original paper. However, I do not (currently) have access to doi:10.1016/0029-5582(65)90348-2 but I plan on hitting the library to order the article and read it for myself (I'm French so that's no issue). Headbomb {talk / contribs / physics / books} 19:06, 10 March 2016 (UTC)

I've got the article with me. Here's my (quick, and thus error prone) translation of some relevant sections, with stuff in bold being my own emphasis

A. Petermann (1963) "Properties of strangeness and a mass formula for vector mesons", Nuclear Physics 63, 349-652

Despite the success of the Gell-Mann--Okubo formula[1] to reproduce the difference in masses for the ordinary baryons (nucleons, Λ, Σ, Ξ), it has been powerless to yield insights about the masses of vector mesons. The goal of this note is to compensate for this deficiency and to give, at least on a provisional basis, a dynamic explication of the role of strangeness in these mass formulae. To this effect, let us consider two spinors, s and s' (their antispinors being denoted by s and s'), s' being strange (|S| = 1) while s is not. The electromagnetic and weak interactions are decoupled so we only consider the realm of strong interactions, much stronger than the other two. We note that if the electromagnetic interaction were present, we would be obliged to consider 3 spinors, s, ŝ and s', that is the isospinor (ŝ, s) with S = 0 and the isoscalar with |S| = 1. [Paragraph on conservation of strangeness, Lagrangian invariance, gauge fields, to argue that a self mass effect proportional to S2(σ2/4π) exists, which means the mass of s' is greater than that of s] In addition, if S2(σ2/4π) were the real coupling constant, we would have a mass increase proportional to S2, while the real mass increase is linear: 1/2 (Ξ+N) ≈ 1/2 (Σ+Λ). This forces us to assign, respectively, the values of S = 0 and |S| = 1 to the strangeness of s and s' (0 and 1 for s and s'), and to consider particles of higher strangeness (the Ξ for example) to be composed of s and s' particles, and rather than being elementary. Then, maintaining the principle according to which, when we neglect on top of electromagnetic and interactions, strangeness, the ordinary baryons offer a complete degeneracy (N = Λ = Σ = Ξ), and if Ξ is composed of s and s', so are the other baryons. In order to be able to construct them from s and s', no s and s' can be involved, otherwise the s's' could intervene, in such a way that ordinary baryons of strangeness S = 0 could be heavier than ordinary baryons of greater strangeness, which is experimentally excluded[†]. This implies that these last ones must be composed of three s at least, without s, because there exist a baryon of strangeness |S| = 2. And so we find the linear increase of mass with strangeness. (We can make the useful comparison to the effects, which in nuclei, are proportional to Ze2 and not Z2e2, explained by the fact that nuclei are conglomerates of Z particles of charge e, and not, themselves, particles of charge Ze.) We then see that the so-called elementary particles like N, Σ, Ξ, etc. are complicated objects, in reality strongly bound states of elementary spinorial particles. But their dynamics is beyond the scope of current field theory. [More stuff on s, ŝ and s', and the implication for the vector meson nonet, assignments of ρ = ss, K* = ss, φ = s's', ω = ss, why mass does not increase linearly with S for mesons and to a variety of mass relations between mesons, in particular $m_{\phi }=2m_{K*}-m_{\rho }$ (eq. 1)] In addition, if we introduce a Z parameter, analogous to the number of protons in a nucleus, and which here specifies the number of s and s' involved in the formation of a vector meson, a mass formula can be written for them as: $m_{\mathrm {v} }=A+BZ$ (eq. 2) where mv is the masss of the vector meson. The A constant is immediately given by experiment, it is the mass of the ρ for with Z = 0. So A = mρ. The B constant is the mass difference between an s' particle and an s particle. From the baryonic mass spectrum, especially baryonic resonances, which is still undergoing in light of the present considerations, B can be estimated to be 140±20 MeV. This estimation, neglects as we have previously done to establish (eq. 1), the difference in binding energy between s' and s', as well that of s and s, before the absolute value of binding energies and masses in play. We then obtain (1) Z = 0: mρ = mω (2) Z = 1: mK* = mρ + (140±20) MeV (3) Z = 2: mφ = mρ + 2(140±20) MeV = mK* + (140±20) MeV The agreement with observed values are good if we take into account experimental errors which are very probably greater than the change affection binding energies between s's' and ss', which we neglected as stated below. In conclusion, we can make the following comments: 1) The presented model, is by all admissions, fairly crude as it cannot address the difference in binding energies mentioned. 2) When the electromagnetic interaction is present, difficulties involved electric charge arises, either in the form of a non-conservation of charge when s particles bind to form the particles we observe in physics. Or if we want to conserve charge, which is highly desirable, s particles must then have non-integer values of charge. This is unpleasant, but cannot, after all, be excluded on physical basis. Other biases might after all be possible to alleviate this difficulty. However, the hypothesis of the strange field as a corollary to the conservation of strangeness gives a dynamic explanation to the fact that a strange particle is heavier than a particle without strangeness, regardless of the sign of strangeness of that particle. As such, this model follows from a rigorous logic. In particular, it give exact informations on the difference of masses of vector mesons and their curious dependence on strangeness. † The presence of an s is also excluded if we want to be able to construct all the families of known baryons, and only them. [1] M. Gell-Mann, Phys Rev 125 (1962) 1067; S. Okubo, Prog. Theor. Phys. 27 (1962) 949

Based on this, I think it's fair to say that Petermann did independently propose quarks, as Petrov claimed in arXiv:1412.8681, and needs to be given his due in this article. Does anyone disagree? Headbomb {talk / contribs / physics / books} 15:27, 18 March 2016 (UTC)

It seems plausible that Petermann deserves some credit, however it is also not Wikipedia's place to correct historical wrongs. We should attribute credit as is done in reliable secondary sources. The only thing we have remotely in that direction is the preprint from Petrov. Petrov seems real careful and doesn't actually goes as far as saying that Petermann deserves credit here. (It doesn't help that we have no record of Petermann asserting he deserves some credit.) I am not opposed to mentioning Petermann's contribution per se, put if we do it would need to be a very careful statement, certainly not bolder than what Petrov says. Due you have any specific suggestions as to how you would mention Petermann's contribution to the development of quarks as an idea?TR 13:45, 19 March 2016 (UTC)

I'm not exactly sure how I would phrase things exactly, but I agree that mirroring Petrov's wording is probably the best path forward (the published version of the preprint is in ISBN 9789814689311 I believe, and the CERN Courier note he refers to is [8]). However, Petrov does write "With all that I believe it would be fair to agree that three quarks (under various names) were discovered independently by the “Splendid Triplet”: Petermann, Gell-Mann and Zweig." which would put Petermann on equal footing with Gell-Mann and Zweig. Headbomb {talk / contribs / physics / books} 15:55, 19 March 2016 (UTC)

Digging deeper, I also find reference to Petermann and quarks in [9] and [10]. There is possibly a reference to it in [11], chapter 7 as well. Headbomb {talk / contribs / physics / books} 16:17, 19 March 2016 (UTC)

I do not recall whether it was I who introduced the Petermann reference, but, despite the fact his submittal date is 1 week before Gell-Mann's and 3 weeks before Zweig's, his contribution is definitely less salutary--he focussed too much on vector mesons, and replicated a lot of the thinking of the much earlier Sakata model, known to all of the above, also quite successful with mesons---but not baryons. He is not much bothered by fractional charges, which Gell Mann clearly is. Gell-Mann, of course, comments that the higher mass of the s quark dictates the weak instability of strangeness; and, more importantly, and completely beyond the reach of both Petermann and Gell-Mann, Zweig appreciates why the φ is so unnaturally long lived, by dint of "Zweig's rule" dynamics. As Gell-Mann has indicated in several memoirs, he was obviously aware of the mathematical possibility of triplet constitutents, but was cowed by their fractional baryon number and charges, and decided to put this in very short print to get insistent questioners like Serber off his back.

So, in a way, Zweig and Gell-Mann did add something new to the landscape, when Petermann just reiterated basic model-building positions know to most at the time... Mind you, even after these papers appeared, most of the community considered it as "charlatan" stuff [cf. Zweig's memoir papers/talks]. So, my own sense is that Petermann certainly deserves a reference to his paper, but not exactly full credit, which unthinking revisionist history is often all too keen to award.Cuzkatzimhut (talk) 16:02, 21 March 2016 (UTC)

I wouldn't agree that this is a Sakata+ type of model. Sakata proposed p, n, Λ as fundamental, and the other hadrons build from them. Peterman, clearly ascribes 3 constituent to all baryons (qqq), and mesons to be qq, with his s, ŝ and s' being called u, d, s in modern parlance. And he flags fractional charges (without doing the math) as unpleasant, but not forbidden by any known physics (which again, was correct then, and still is now). I, like Petrov, can offer no explanation for why this was forgotten until the note in CERN Courier. But I'm trying to see how Petermann's proposal differs from that of Zweig or Gell-Mann, and I can't see any difference between Petermann's s particles, Gell-Mann's quarks, and Zweig's aces. Each of the original papers address different aspects and consequences of composite hadrons / quarks, but they all nail the quark thing. Headbomb {talk / contribs / physics / books} 16:13, 21 March 2016 (UTC)

Yes, of course, they are talking about the same thing, which, according to an uncontested letter by Serber, he, too was working out in the spring of 63, cf Zweig. I brought up Sakatons since the decisive point in GM's paper was the baryons--I mean, he had speculated about hadron constituents in the original eightforld way preprint, but then got cold feet in the paper. My sense is that all of these efforts fit into a continuum, with nuance and emphasis playing a role in how they were received. Zweig, by contrast, had the insight as to why these quarks might be "real" ("dynamical"): they did something beyond streamlining the group theory! Cuzkatzimhut (talk) 16:29, 21 March 2016 (UTC)

I agree there's a continuum, and you can pretty much trace it from discoveries -> strangeness -> Sakata model (which we should probably mention more in this article) -> Eightfold Way -> Quarks. Petermann's s particles were speculative too, but no less real than Zweig's, and give a physical basis for the Gell-Mann Okubo mass formula, just as much as Gell-Mann's quarks does. If I had to give a difference between Gell-Mann and Peterman, the only thing I can come up with is that Gell-Mann and Zweig speculated on the implications, and both predicted the Omega that way. Petermann kept to known hadrons, and it's anyone's guess as to why he didn't speculate, because that prediction was right there. I don't see that different to be big enough to say Petermann didn't propose quarks.

As for Petermann and Serber, well Serber didn't publish, so though luck for him. Headbomb {talk / contribs / physics / books} 18:15, 21 March 2016 (UTC)

Sure, I would not advocate giving much credit to Serber---I only wanted to illustrate the continuum. NB: the Omega minus, coincidentally observed next month, Feb 64, had little to do with the quark model. It was the jewel in the crown of the baryon decuplet of the eightfold way, largely accepted back then. My only urge for delicacy and a soft touch in "evaluating" Petermann, beyond adducing the reference, which certainly belongs, is that, he is beginning to fit into a new narrative promulgated by CERN, in an effort to efface its dark role in the Zweig preprints, after over half a century... (Well, that means VanHove, not quite the lab itself, but...) CERN would not even have Zweig's preprints typed, and went out of its way to damp and malign the message... Their new tack is, "so, what's the big deal, lots of people got there!" I gather NPOV language could do wonders here, but "splendid triplet" would raise hackles and launch the screamers.... Cuzkatzimhut (talk) 18:37, 21 March 2016 (UTC)

Right you are on the Omega, that's Eightfold way stuff, not quark model stuff. So that's one less difference between their proposals. And I think we can all agree on leaving out that sort of flowery language from here. Headbomb {talk / contribs / physics / books} 18:56, 21 March 2016 (UTC)

Can someone please revert to the long standing FA version?

WilliamJennings1989 (talk · contribs) has been running amok, weakening the prose and grammar of this FA article for the past few days, and edit warring over matters of (long-established and stable) style in violation of WP:MOS ("Edit warring over optional styles is unacceptable.[b]") using bunk rationale (e.g. [12], removing dashes just because he doesn't like them, claiming 'more than two per sentence' makes it unclear. This would be valid if true, but the sentence in question only had two endashes, not 3+).

Can someone else revert his edits, because we're dealing with a major case of WP:IDIDNTHEARTHAT and I don't feel like getting blocked for violations of WP:3RR. Headbomb {talk / contribs / physics / books} 14:51, 4 April 2016 (UTC)

Headbomb (talk · contribs) Is lying, and deleting contributions in a manner that is unwelcome to public participation. He is edit warring and repeatedly changing his rationale for doing so. I have separated a run-on sentence into two parts by removing dashes because the WP:MOS says specifically that: "Using commas ... interrupts a sentence less than using round brackets or dashes to express parenthetical material." Headbomb does not recognize a direct quotation from the WP:MOS as a valid claim. It should be valid and true to use the exact wording from WP:MOS to explain an edit. The point I make thereof refers more to the clarity of the sentence than the number of dashes. In any case, we are instructed to "use dashes sparingly".

Please note that I am not whining about his misbehavior in the other section. Rather, I am seeking to explain myself in a less constrained context and perhaps enjoy a discussion on this issue. If he has to worry about getting blocked, then maybe he is not benefiting Wikipedia after all.WilliamJennings1989 (talk) 15:12, 4 April 2016 (UTC)

I have ~140,000 contributions on this Encyclopedia, poured several thousand of hours of my own time both in article space and behind the scene, copy edited thousands of article, and one (amongst several) of the major authors of this feature article. Do not, for even one second, suggest, imply, or otherwise hint that I'm WP:NOTHERE for the benefit of the project. Headbomb {talk / contribs / physics / books} 15:27, 4 April 2016 (UTC)

If someone has to complain about getting blocked, then it stands to reason that he or she might not be doing a good job. Headbomb sounds like an obsessive-compulsive because he is changing the subject to his own attachment, and then using an imperative against anyone who would question that attachment. I have responded to him politely in kind, and he still does not recognize my references to the subject matter.WilliamJennings1989 (talk) 15:32, 4 April 2016 (UTC)

Simply put, you are edit warring over long-established matters of style (~7 years) in violation of WP:MOS, and WP:ARBCOM sanctions on a Featured article, where the prose has been scrutinized from top to bottom several times. So gain consensus for a style change, and then it can be implemented, or desist. Otherwise it's going to be you on the receiving end of a block. Headbomb {talk / contribs / physics / books} 15:44, 4 April 2016 (UTC)

Headbomb, you are: edit warring instead of being constructive; and making a fallacious claim of establishment without any direct reference by paraphrase or quotation. I am glad that you have finally consented to discussion in the section I started, instead of whining about a potential block on your account. Are you actually threatening to block me for rejecting your unsourced claim on the usage of dashes?WilliamJennings1989 (talk) 16:27, 4 April 2016 (UTC)

Wording, style, and grammar as it pertains to this article.

@Headbomb: The construction dash, comma, dash is always wrong when it introduces an independent clause. That grammatical error is a run-on sentence; especially if a new subject is added like: "that is,". The Wikipedia Manual of Style states that spaced en dashes should be used sparingly, and that commas are less interruptive than dashes. Hence, the sentence should be divided into two parts with commas instead of spaced en dashes.WilliamJennings1989 (talk) 14:57, 4 April 2016 (UTC)

Spaced endashes are equivalent to commas here, and can be used to separate independent clauses (see "parenthetical dashes" in WP:DASH). Pick any manual of style, or go through WP:DASH, where the example "The birds—at least the ones Darwin collected—had red and blue feathers." is listed (and it is understood that spaced endashes are equivalent to unspaced emdashes). Headbomb {talk / contribs / physics / books} 15:50, 4 April 2016 (UTC)

At last, Headbomb has acknowledged my attempt to gain consensus! The example in WP:DASH uses a dependent clause, "at least the ones Darwin collected". Specifically, the object "at least the ones" depends on the subject "The birds". We both understand that emdashes should not be spaced, and that dashes are generally equivalent. The problem is that the FA version of the article shoves a separate sentence within two dashes. It is obvious enough if you omit the comma following "that is", and means the same thing.WilliamJennings1989 (talk) 16:27, 4 April 2016 (UTC)

Sakata model

I feel this should be mentioned in the history section, but I'm not quite sure where or how. Opinions? Headbomb {talk / contribs / physics / books} 23:48, 12 September 2016 (UTC)

I added something in the History section. A perfectly serviceable discussion is found in the quark model article, but not every reader of this article will go there. Hand-wringing about Sakatons has colored NP deliberations to the detriment of deserved recognition of the feat. Cuzkatzimhut (talk) 15:31, 20 September 2016 (UTC)

Status of Higgs Boson

In relation to the recent reversion of my edit, in what way is the status of the Higgs boson still "under debate"? CERN scientists say that the particle discovered is a Higgs boson, they just don't know yet what kind of Higgs boson it is. A look at the Higgs boson Wikipedia page gives this: "The Higgs boson or Higgs particle is an elementary particle initially theorised in 1964, whose discovery was announced at CERN on 4 July 2012." So, we have the situation that people reading Wikipedia will be confused, there is conflicting information, is it or not a currently existing particle? CERN have announced its discovery. CMS spokesman Joe Incandela announced (http://home.web.cern.ch/about/updates/2013/03/new-results-indicate-new-particle-higgs-boson ) “The preliminary results with the full 2012 data set are magnificent and to me it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is,”. The scientific community has accepted that the new particle is indeed a Higgs boson. Whether it is the Standard Model Higgs boson or not is a different question, but it has been accepted as an existing particle. — Preceding unsigned comment added by Quadrupedi (talk • contribs) 09:01, 29 November 2013 (UTC)

Antiquarks in the header

Antiquarks are mentioned but their individual names aren't given. Since someone might think that since up and down are opposite that the quarks of that name are each other's antiparticle I added a quick sentence about antiup, antidown, etc. MeDrewNotYou (talk) 16:05, 13 March 2016 (UTC)

I think its not C, its D!! I mean that the quarks have Dimensional properties, not color properties!! Hamdantec (talk) 17:38, 21 September 2016 (UTC)