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'In particle physics, '''B mesons''' are [[meson]]s composed of a [[bottom antiquark]] and either an [[up quark|up]] ({{Subatomic particle|B+}}), [[down quark|down]] ({{Subatomic particle|B0}}), [[strange quark|strange]] ({{Subatomic particle|Strange B0}}) or [[charm quark|charm]] [[quark]] ({{Subatomic particle|Charmed B+}}). The combination of a bottom antiquark and a [[top quark]] is not thought to be possible because of the top quark's short lifetime. The combination of a bottom antiquark and a bottom quark is not a B meson, but rather ''[[bottomonium]]''. Each B meson has an [[antiparticle]] that is composed of a bottom quark and an [[up quark|up]] ({{Subatomic particle|B-}}), [[down quark|down]] ({{Subatomic particle|AntiB0}}), [[strange quark|strange]] ({{Subatomic particle|Strange antiB0}}) or [[charm quark|charm]] antiquark ({{Subatomic particle|Charmed b-}}) respectively. == List of B mesons == <center> {| class="wikitable sortable" style="text-align:center" |+ B mesons ! Particle ! Symbol ! Anti-particle ! class="unsortable"|[[Quark]]<br>content ! Charge ! [[Isospin]]<br>([[Isospin|I]]) ! [[Spin (physics)|Spin]] and [[Parity (physics)|parity]]<br>([[spin (physics)|J]]^{[[Parity (physics)|P]]}) ! [[Rest mass]]<br>([[electron volt|MeV]]/[[speed of light|c]]²) ! [[strangeness|S]] ! [[charm (quantum number)|C]] ! [[bottomness|B']] ! [[Mean lifetime]]<br>([[second|s]]) ! Commonly decays to |- | B meson | {{Subatomic particle|B+}} | {{Subatomic particle|B-}} | {{Subatomic particle|Up quark}}{{Subatomic particle|Bottom antiquark}} | +1 | {{frac|1|2}} | 0⁻ | {{val|5279.15|0.31}} | 0 | 0 | +1 | {{val|1.638|0.011|e=-12}} | See [http://pdg.lbl.gov/2010/tables/rpp2010-tab-mesons-bottom.pdf {{Subatomic particle|B+-}} decay modes] |- | B meson | {{Subatomic particle|B0}} | {{Subatomic particle|AntiB0}} | {{Subatomic particle|Down quark}}{{Subatomic particle|Bottom antiquark}} |0 | {{frac|1|2}} | 0⁻ | {{val|5279.53|0.33}} | 0 | 0 | +1 | {{val|1.530|0.009|e=-12}} | See [http://pdg.lbl.gov/2010/tables/rpp2010-tab-mesons-bottom.pdf {{Subatomic particle|B0}} decay modes] |- | [[Strange B meson]] | {{Subatomic particle|Strange b0}} | {{Subatomic particle|Strange AntiB0}} | {{Subatomic particle|Strange quark}}{{Subatomic particle|Bottom antiquark}} |0 | 0 | 0⁻ | {{val|5366.3|0.6}} | −1 | 0 | +1 | {{val|1.470|+0.027|-0.026|e=-12}} | See [http://pdg.lbl.gov/2010/tables/rpp2010-tab-mesons-bottom-strange.pdf {{Subatomic particle|Strange B0}} decay modes] |- | [[Charmed B meson]] | {{Subatomic particle|Charmed b+}} | {{Subatomic particle|Charmed b-}} | {{Subatomic particle|Charm quark}}{{Subatomic particle|Bottom antiquark}} | +1 | 0 | 0⁻ | {{val|6276|4}} | 0 | +1 | +1 | {{val|0.46|0.07|e=-12}} | See [http://pdg.lbl.gov/2010/tables/rpp2010-tab-mesons-bottom-charm.pdf {{Subatomic particle|Charmed B+-}} decay modes] |} </center> == {{Subatomic particle|B}}–{{Subatomic particle|AntiB}} oscillations == {{Main|B-Bbar oscillation|l1={{Subatomic particle|B}}–{{Subatomic particle|AntiB}} oscillation}} The neutral B mesons, {{Subatomic particle|B0}} and {{Subatomic particle|Strange b0}}, spontaneously transform into their own antiparticles and back. This phenomenon is called [[Neutral particle oscillation|flavor oscillation]]. The existence of neutral B meson oscillations is a fundamental prediction of the [[Standard Model]] of [[particle physics]]. It has been measured in the {{Subatomic particle|B0}}–{{Subatomic particle|AntiB0}} system to be about {{nowrap|0.496 [[picosecond|ps]]⁻¹}},<ref>http://repository.ubn.ru.nl/bitstream/2066/26242/</ref> and in the {{Subatomic particle|Strange b0}}–{{Subatomic particle|Strange antib0}} system to be {{nowrap|Δ''m''_s {{=}} 17.77 ± 0.10 (stat) ± 0.07 (syst) ps⁻¹}} measured by [[CDF experiment]] at [[Fermilab]].<ref> {{cite journal |author=A. Abulencia ''et al.'' ([[Collider Detector at Fermilab|CDF Collaboration]]) |year=2006 |title=Observation of {{Subatomic particle|Strange B0}}–{{Subatomic particle|Strange antiB0}} Oscillations |journal=[[Physical Review Letters]] |volume=97 |pages=242003 |doi=10.1103/PhysRevLett.97.242003 |id= |arxiv=hep-ex/0609040 |bibcode=2006PhRvL..97x2003A |issue=24 }}</ref> A first estimation of the lower and upper limit of the {{Subatomic particle|Strange b0}}–{{Subatomic particle|Strange antib0}} system value have been made by the [[DØ experiment]] also at [[Fermilab]].<ref> {{cite journal |author=V.M. Abazov ''et al.'' ([[DØ experiment|D0 Collaboration]]) |year=2006 |title=Direct Limits on the B_s⁰ Oscillation Frequency |url=http://www-d0.fnal.gov/www_buffer/pub/pub_287.pdf |journal=[[Physical Review Letters]] |volume=97 |pages=021802 |doi=10.1103/PhysRevLett.97.021802 |bibcode=2006PhRvL..97b1802A |arxiv = hep-ex/0603029 |issue=2 }}</ref> On 25 September 2006, [[Fermilab]] announced that they had claimed discovery of previously-only-theorized B_s meson oscillation.<ref> {{cite press release |publisher=[[Fermilab]] |date=25 September 2006 |title=It might be…It could be…It is!!! |url=http://www.fnal.gov/pub/presspass/press_releases/CDF_meson.html |accessdate=2007-12-08 }}</ref> According to Fermilab's press release: <blockquote>This first major discovery of Run 2 continues the tradition of particle physics discoveries at Fermilab, where the bottom (1977) and top (1995) quarks were discovered. Surprisingly, the bizarre behavior of the B_s (pronounced "B sub s") mesons is actually predicted by the Standard Model of fundamental particles and forces. The discovery of this oscillatory behavior is thus another reinforcement of the Standard Model's durability...<p> CDF physicists have previously measured the rate of the matter-antimatter transitions for the B_s meson, which consists of the heavy bottom quark bound by the strong nuclear interaction to a strange antiquark. Now they have achieved the standard for a discovery in the field of particle physics, where the probability for a false observation must be proven to be less than about 5 in 10 million (5/10,000,000). For CDF's result the probability is even smaller, at 8 in 100 million (8/100,000,000).</blockquote> Ronald Kotulak, writing for the [[Chicago Tribune]], called the particle "bizarre" and stated that the meson "may open the door to a new era of physics" with its proven interactions with the "spooky realm of antimatter".<ref> {{cite news |author=R. Kotulak |url=http://deseretnews.com/dn/view/0,1249,650194039,00.html |date=26 September 2006 |title=Antimatter discovery could alter physics: Particle tracked between real world, spooky realm |work=[[Deseret News]] |accessdate=2007-12-08 | archiveurl= http://web.archive.org/web/20071129012130/http://deseretnews.com/dn/view/0,1249,650194039,00.html| archivedate= 29 November 2007 <!--DASHBot-->| deadurl= no}}</ref> On 14 May 2010, physicists at the Fermi National Accelerator Laboratory reported that the oscillations decayed into matter 1% more often than into antimatter, which may help explain the abundance of matter over antimatter in the observed Universe.<ref>[http://www.nytimes.com/2010/05/18/science/space/18cosmos.html?src=me&ref=general A New Clue to Explain Existence]</ref> However, more recent results at [[LHCb]] with larger data samples have suggested no significant deviation from the Standard Model.<ref>[http://arstechnica.com/science/news/2011/08/lhcb-detector-causes-trouble-for-supersymmetry.ars Article on LHCb results]</ref> == See also == *[[B–Bbar oscillation|B–{{Subatomic particle|Antib}} oscillation]] ==References== {{reflist}} ==External links== *[http://pdg.lbl.gov/2007/listings/s091.pdf W.-M. Yao ''et al.'' (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL: http://pdg.lbl.gov)] *{{cite web |author=V. Jamieson |date=18 March 2008 |title=Flipping particle could explain missing antimatter |url=http://www.newscientist.com/channel/fundamentals/mg19726483.600-flipping-particle-could-explain-missing-antimatter.html?feedId=online-news_rss20 |work=[[New Scientist]] |accessdate=2010-01-23 }} {{Particles}} {{Use dmy dates|date=December 2011}} [[Category:Mesons]]'