View source for Physics:B meson

{{Infobox particle
| name = B meson
| image = 
| caption = 
| num_types = 
| composition = {{plainlist|
*{{Subatomic particle|B+}}: {{Subatomic particle|Up quark}}{{Subatomic particle|Bottom antiquark}}
*{{Subatomic particle|B0}}: {{Subatomic particle|Down quark}}{{Subatomic particle|Bottom antiquark}}
*{{Subatomic particle|strange B0}}: {{Subatomic particle|Strange quark}}{{Subatomic particle|Bottom antiquark}}
*{{Subatomic particle|charmed B+}}: {{Subatomic particle|Charm quark}}{{Subatomic particle|Bottom antiquark}}}}
| statistics = [[Physics:Bosonic|Bosonic]]
| group = [[Physics:Meson|Meson]]s
| interaction = [[Physics:Strong interaction|Strong]], [[Physics:Weak interaction|Weak]], Gravitational, Electromagnetic
| antiparticle = {{plainlist|
*{{Subatomic particle|B+}}: {{Subatomic particle|B-}}
*{{Subatomic particle|B0}}: {{Subatomic particle|antiB0}}
*{{Subatomic particle|strange B0}}: {{Subatomic particle|strange antiB0}}
*{{Subatomic particle|charmed B+}}: {{Subatomic particle|charmed B-}}}}
| status = 
| theorized = 
| discovered = 
| symbol = {{Subatomic particle|B+}}, {{Subatomic particle|B-}}, {{Subatomic particle|B0}}, {{Subatomic particle|antiB0}}, {{Subatomic particle|strange B0}}, {{Subatomic particle|strange antiB0}}, {{Subatomic particle|charmed B+}}, {{Subatomic particle|charmed B-}}
| mass = {{plainlist|
*{{Subatomic particle|B+}}: {{val|5279.34|0.12|ul=MeV/c2}}
*{{Subatomic particle|B0}}: {{val|5279.65|0.12|u=MeV/c2}}
*{{Subatomic particle|strange B0}}: {{val|5366.88|0.14|u=MeV/c2}}
*{{Subatomic particle|charmed B+}}: {{val|6274.9|0.8|u=MeV/c2}}
}}
| mean_lifetime = {{plainlist|
*{{Subatomic particle|B+}}: {{val|1.638|0.004|e=-12|u=s}}
*{{Subatomic particle|B0}}: {{val|1.519|0.004|e=-12|u=s}}
*{{Subatomic particle|strange B0}}: {{val|1.515|0.004|e=-12|u=s}}
*{{Subatomic particle|charmed B+}}: {{val|0.510|0.009|e=-12|u=s}}
}}
| decay_particle = 
| electric_charge = {{plainlist|
*{{Subatomic particle|B+-}}, {{Subatomic particle|charmed B+-}}: ±1 [[Physics:Elementary charge|e]]
*{{Subatomic particle|B0}}, {{Subatomic particle|strange B0}}: 0 [[Physics:Elementary charge|e]]
}}
| spin = 0
| strangeness = {{Subatomic particle|strange B0}}: −1
| charm = {{Subatomic particle|charmed B+}}: +1
| bottomness = +1
| topness = 
| isospin = {{plainlist|
*{{Subatomic particle|B+}}: +{{frac|1|2}}
*{{Subatomic particle|B0}}: −{{frac|1|2}}
*{{Subatomic particle|strange B0}}, {{Subatomic particle|charmed B+}}: 0
}}
| hypercharge = 
| parity = −1
| c_parity = 
}}
In [[Physics:Particle physics|particle physics]], '''B mesons''' are [[Physics:Meson|meson]]s composed of a [[Physics:Bottom quark|bottom]] [[Physics:Antiquark|antiquark]] and either an [[Physics:Up quark|up]] ({{Subatomic particle|B+}}), [[Physics:Down quark|down]] ({{Subatomic particle|B0}}), [[Physics:Strange quark|strange]] ({{Subatomic particle|Strange B0}}) or [[Physics:Charm quark|charm]] [[Physics:Quark|quark]] ({{Subatomic particle|Charmed B+}}). The combination of a bottom antiquark and a [[Physics:Top quark|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'', which is something else entirely.

Each B meson has an [[Physics:Antiparticle|antiparticle]] that is composed of a bottom quark and an [[Physics:Up quark|up]] ({{Subatomic particle|B-}}), [[Physics:Down quark|down]] ({{Subatomic particle|AntiB0}}), [[Physics:Strange quark|strange]] ({{Subatomic particle|Strange antiB0}}) or [[Physics:Charm quark|charm]] ({{Subatomic particle|Charmed b-}}) antiquark respectively.

==List of B mesons==
{| class="wikitable sortable" style="margin:1em auto; text-align:center"
|+ B mesons
|-
! Particle
! Symbol 
! Anti-<br/>particle 
! class="unsortable" | [[Physics:Quark|Quark]] <br />content
! Charge
! [[Physics:Isospin|Isospin]] <br />([[Physics:Isospin|I]])
! [[Physics:Spin|Spin]] and [[Physics:Parity|parity]], <br />([[Physics:Spin|J]]<sup>[[Physics:Parity|P]]</sup>)
! [[Physics:Rest mass|Rest mass]] <br />(MeV/[[Physics:Speed of light|''c'']]<sup>2</sup>)
! [[Physics:Strangeness|S]]
! [[Physics:Charm (quantum number)|C]]
! [[Physics:Bottomness|B']]
! Mean lifetime ([[Second|s]])
! Commonly decays to
|-
| Charged<br/>B meson
| {{Subatomic particle|B+}}
| {{Subatomic particle|B-}}
| {{Subatomic particle|Up quark}}{{Subatomic particle|Bottom antiquark}}
| +1
| {{sfrac|1|2}}
| 0<sup>−</sup>
| {{val|5279.34|0.12}}
| 0
| 0
| +1
| {{val|1.638|0.004|e=-12}}
| See [http://pdg.lbl.gov/2022/listings/rpp2022-list-B-plus-minus.pdf {{Subatomic particle|B+-}} decay modes]
|-
| Neutral<br/>B meson
| {{Subatomic particle|B0}}
| {{Subatomic particle|AntiB0}}
| {{Subatomic particle|Down quark}}{{Subatomic particle|Bottom antiquark}}
|0
| {{sfrac|1|2}}
| 0<sup>−</sup>
| {{val|5279.65|0.12}}
| 0
| 0
| +1
| {{val|1.519|0.004|e=-12}}
| See [http://pdg.lbl.gov/2022/listings/rpp2022-list-B-zero.pdf {{Subatomic particle|B0}} decay modes]
|-
| [[Physics:Strange B meson|Strange B meson]]
| {{Subatomic particle|Strange b0}}
| {{Subatomic particle|Strange AntiB0}}
| {{Subatomic particle|Strange quark}}{{Subatomic particle|Bottom antiquark}}
|0
| 0
| 0<sup>−</sup>
| {{val|5366.88|0.14}}
| −1
| 0
| +1
| {{val|1.515|0.004|e=-12}}
| See [http://pdg.lbl.gov/2022/tables/rpp2022-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<sup>−</sup>
| {{val|6274.9|0.8}}
| 0
| +1
| +1
| {{val|0.510|0.009|e=-12}}
| See [http://pdg.lbl.gov/2022/tables/rpp2022-tab-mesons-bottom-charm.pdf {{Subatomic particle|Charmed B+-}} decay modes]
|}

=={{Subatomic particle|B0}}–{{Subatomic particle|AntiB0}} oscillations==
The neutral B mesons, {{Subatomic particle|B0}} and {{Subatomic particle|Strange B0}}, spontaneously transform into their own antiparticles and back. This phenomenon is called [[Physics:Neutral particle oscillation|flavor oscillation]]. The existence of neutral B meson oscillations is a fundamental prediction of the [[Physics:Standard Model|Standard Model]] of [[Physics:Particle physics|particle physics]]. It has been measured in the {{Subatomic particle|B0}}–{{Subatomic particle|AntiB0}} system to be about {{nowrap|0.496 / [[Picosecond|picosecond]]s}},<ref>{{cite web |url=http://repository.ubn.ru.nl/bitstream/2066/26242/ |title=[no title cited] |id=2066/26242 |website=repository.ubn.ru.nl }}</ref> and in the {{Subatomic particle|Strange b0}}–{{Subatomic particle|Strange antib0}} system to be {{nowrap|Δ''m''<sub>s</sub> {{=}} 17.77 ± 0.10 (stat) ± 0.07 (syst) / [[Picosecond|picosecond]]}} measured by [[Physics:Collider Detector at Fermilab|CDF]] experiment at [[Organization:Fermilab|Fermilab]].<ref>{{cite journal |last1=Abulencia |first1=A. |display-authors=0 |collaboration=[[Physics:Collider Detector at Fermilab|CDF Collaboration]] |year=2006 |title=Observation of {{Subatomic particle|Strange B0}}–{{Subatomic particle|Strange antiB0}} Oscillations  |doi=10.1103/PhysRevLett.97.242003 |journal=[[Physics:Physical Review Letters|Physical Review Letters]] |volume=97 |issue=24 |pages=242003 |arxiv=hep-ex/0609040 |bibcode=2006PhRvL..97x2003A |pmid=17280271}}</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 [[Physics:DØ experiment|DØ experiment]] also at  [[Organization:Fermilab|Fermilab]].<ref>{{cite journal |last1=Abazov |first1=V. M. |display-authors=0 |collaboration=[[Physics:DØ experiment|D0 Collaboration]] |year=2006 |title=Direct Limits on the B{{su|b=s|p=0}} Oscillation Frequency |doi=10.1103/PhysRevLett.97.021802 |journal=[[Physics:Physical Review Letters|Physical Review Letters]] |volume=97 |issue=2 |page=021802 |arxiv=hep-ex/0603029 |bibcode=2006PhRvL..97b1802A |pmid=16907434 |hdl=10211.3/194397 |s2cid=11632404 |url=http://www-d0.fnal.gov/www_buffer/pub/pub_287.pdf}}</ref>

On 25 September 2006, [[Organization:Fermilab|Fermilab]] announced that they had claimed discovery of previously-only-theorized B<sub>s</sub> meson oscillation.<ref>{{cite press release |publisher=[[Organization:Fermilab|Fermilab]] |date=25 September 2006 |title=Fermilab's CDF scientists make it official: They have discovered the quick-change behavior of the B-sub-s meson, which switches between matter and antimatter 3&nbsp;trillion times a second |url=http://www.fnal.gov/pub/presspass/press_releases/CDF_meson.html |access-date=8 December 2007}}</ref> According to Fermilab's press release:

<blockquote>This first major discovery of Run&nbsp;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{{sub|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&nbsp;...<br/><br/>

CDF physicists have previously measured the rate of the matter-antimatter transitions for the B{{sub|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&nbsp;million ({{frac|5|10,000,000}}). For CDF's result the probability is even smaller, at 8 in 100&nbsp;million {{nowrap|({{frac|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 |last=Kotulak  |first=R. |date=26 September 2006 |title=Antimatter discovery could alter physics: Particle tracked between real world, spooky realm |url=http://deseretnews.com/dn/view/0,1249,650194039,00.html |work=Deseret News |access-date=8 December 2007  |archive-url=https://web.archive.org/web/20071129012130/http://deseretnews.com/dn/view/0%2C1249%2C650194039%2C00.html |archive-date=29 November 2007 |url-status=live }}</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>{{cite news |last1=Overbye |first1=D. |date=17 May 2010 |title=From Fermilab, a New Clue to Explain Human Existence? |url=https://www.nytimes.com/2010/05/18/science/space/18cosmos.html |newspaper={{wipe|The New York Times}} |access-date=26 December 2016 }}</ref> However, more recent results at LHCb with larger data samples have suggested no significant deviation from the Standard Model.<ref>{{cite web |last=Timmer |first=J. |date=29 August 2011 |title=LHCb detector causes trouble for supersymmetry theory |website=[[Ars Technica]] |access-date=26 December 2012  |url=https://arstechnica.com/science/2011/08/lhcb-detector-causes-trouble-for-supersymmetry/}}</ref>

==Rare decays==
B mesons are an important probe for exploring [[Physics:Quantum chromodynamics|quantum chromodynamics]].<ref>{{cite journal |title=Observation of the rare {{nowrap|B{{su|b=s|p=0}} → µ{{sup|+}} µ{{sup|&minus;}}}} decay from the combined analysis of CMS and LHCb data |journal=Nature |date=4 June 2015 |pages=68–72 |volume=522 |issue=7554 |doi=10.1038/nature14474 |pmid=26047778 |author1=CMS Collaboration |author2=LHCb Collaboration|arxiv=1411.4413 |bibcode=2015Natur.522...68C |s2cid=4394036 }}</ref> Various uncommon decay paths of the B&nbsp;mesons are sensitive to physics processes [[Physics:Physics beyond the Standard Model|outside the standard model]]. Measuring these rare branching fractions sets limits on new particles. The LHCb experiment has observed and searched for several of these decays such as {{nowrap|B{{sub|s}} → µ{{sup|+}} µ{{sup|−}}.}}<ref>{{cite journal |title=Search for the rare decays {{nowrap| B{{sup|0}} → J/{{mvar|ψ}} {{mvar|γ}} }} and {{nowrap| B{{su|p=0|b=s}} → J/{{mvar|ψ}} {{mvar|γ}} }} |journal=Physical Review D |volume=92 |issue=11 |pages=112002 |date=16 October 2015 |first1=R. |last1=Aaij |first2=C. Abellán |last2=Beteta  |first3=B. |last3=Adeva |first4=M. |last4=Adinolfi |first5=A. |last5=Affolder |first6=Z. |last6=Ajaltouni |first7=S. |last7=Akar |first8=J. |last8=Albrecht |doi=10.1103/PhysRevD.92.112002 |arxiv=1510.04866 |bibcode=2015PhRvD..92k2002A|s2cid=118320485 }}</ref>

On 21&nbsp;February 2017, the LHCb collaboration announced that the rare decay of a neutral B meson into two oppositely charged kaons had been observed to a statistical significance of 5{{mvar|σ}}.<ref>{{cite journal |title=Observation of the annihilation decay mode {{nowrap| B{{sup|0}} → K{{sup|+}} K{{sup|&minus;}} }} |journal=Physical Review Letters |volume=118 |issue=8 |pages=47–50 |date=21 February 2017  |first1=R. |last1=Aaij |display-authors=0 |pmid=2828221 |doi=10.1103/PhysRevLett.118.081801 |arxiv=1610.08288 |bibcode=2017PhRvL.118h1801A|s2cid=27186492 }}</ref>

==See also==
*[[Physics:B–Bbar oscillation|B–{{Subatomic particle|Antib}} oscillation]]

==References==
{{reflist|30em}}

==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 book |last=Stone |first=Sheldon |title=B Decays |date=1994 |publisher=[[Company:World Scientific|World Scientific]] |location=Syracuse Univ. |doi=10.1142/1441 |isbn=978-981-02-0708-3 |edition=2nd |url=https://doi.org/10.1142/1441 |oclc=636743000}}
*{{cite web |author=V. Jamieson |date=18 March 2008 |title=Flipping particle could explain missing antimatter |url=https://www.newscientist.com/channel/fundamentals/mg19726483.600-flipping-particle-could-explain-missing-antimatter.html |work=New Scientist |access-date=23 January 2010}}

{{Particles}}


[[Category:Mesons]]
[[Category:B physics]]

{{Sourceattribution|B meson}}