View source for Strange B meson

{{Technical|date=September 2010}}

{{Infobox particle
| name = {{Subatomic particle|Strange B}} meson
| image = Quark structure strange B meson.svg
| caption = The [[quark]] structure of the strange B meson. The color assignment of individual quarks is arbitrary, but the net [[color charge]] must be zero. Forces between quarks are mediated by [[gluons]].
| num_types = 
| composition = {{Subatomic particle|bottom antiquark|link=yes}}{{Subatomic particle|Strange quark|link=yes}}
| statistics = [[Bosonic]]
| group = [[Meson]]s
| interaction = [[Strong interaction|Strong]], [[Weak interaction|Weak]], [[Gravitational]], [[Electromagnetic]]
| antiparticle = {{Subatomic particle|Strange antib}} ({{Subatomic particle|bottom quark|link=yes}}{{Subatomic particle|Strange antiquark|link=yes}})
| status = 
| theorized = 
| discovered = 
| symbol = 
| mass = {{val|5366.3|0.6|ul=MeV/c2}}
| mean_lifetime = {{val|1.470| 0.027|-0.026|e=-12|u=s}}
| decay_particle = [http://pdg.lbl.gov/2008/tables/rpp2008-tab-mesons-bottom-strange.pdf See {{Subatomic particle|Strange B0}} decay modes]
| electric_charge = 0&nbsp;[[Elementary charge|e]]
| spin = 0
| strangeness = -1
| charm = 
| bottomness = +1
| topness = 
| isospin = 0
| hypercharge = 
| parity = -1
| c_parity = 
}}
The '''{{Subatomic particle|Strange b}} meson''' is a [[meson]] composed of a [[bottom quark|bottom antiquark]] and a [[strange quark]]. Its [[antiparticle]] is the '''{{Subatomic particle|Strange antib}} meson''', composed of a bottom quark and a strange antiquark.

== B–B oscillations ==
Strange B mesons are noted for their ability to [[B-Bbar oscillation|oscillate]] between [[matter]] and [[antimatter]] via a [[neutral particle oscillation|box-diagram]] with {{nowrap|Δ''m''<sub>s</sub> {{=}} 17.77 ± 0.10 (stat) ± 0.07 (syst) ps<sup>−1</sup>}} 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 |issue=24
 |pages=242003
 |arxiv=hep-ex/0609040
 |bibcode=2006PhRvL..97x2003A
 |doi=10.1103/PhysRevLett.97.242003
|pmid=17280271
 }}</ref> 
That is, a meson composed of a bottom quark and strange antiquark, the strange {{Subatomic particle|antib}} meson, can spontaneously change into an bottom antiquark and strange quark pair, the strange {{Subatomic particle|b}} meson, and vice versa.

On 25 September 2006, [[Fermilab]] announced that they had claimed discovery of previously-only-theorized B<sub>s</sub> meson oscillation.<ref name="fnal">
{{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:

{{quote|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...

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).<ref name="fnal"/>}}

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
 |archive-url=https://web.archive.org/web/20061018173736/http://deseretnews.com/dn/view/0,1249,650194039,00.html
 |url-status=dead
 |archive-date=18 October 2006
 |date=26 September 2006
 |title=Antimatter discovery could alter physics: Particle tracked between real world, spooky realm
 |work=[[Deseret News]]
 |accessdate=2007-12-08
}}</ref>

Better understanding of the meson is one of the main objectives of the [[LHCb]] experiment conducted at the [[Large Hadron Collider]].<ref>
{{cite web
 |date=June 2008
 |url=http://lhcb.web.cern.ch/lhcb/Hot%20News/Articles/PWJun08gershon.pdf
 |title=A Taste of LHC Physics
 |work=[[Physics World]]
 |pages=22–25
}}</ref>  On 24 April 2013, [[CERN]] physicists in the LHCb collaboration announced that they had observed [[CP violation]] in the decay of strange {{Subatomic particle|b}} mesons for the first time.<ref>
{{cite web
 | date=24 April 2013
 | title=LHCb experiment observes new matter-antimatter difference
 | url=http://press.web.cern.ch/press-releases/2013/04/lhcb-experiment-observes-new-matter-antimatter-difference
 | publisher=[[CERN|CERN Press Office]]
 | accessdate=2013-04-24
}}</ref><ref>
{{cite journal
 |author=R. Aaij ''et al.'' ([[LHCb|LHCb collaboration]])
 |year=2013
 |title=First Observation of C P Violation in the Decays of B s 0 Mesons
 |journal=[[Physical Review Letters]]
 |volume=110 |issue=22 |page=221601
 |arxiv=1304.6173
 |bibcode=2013PhRvL.110v1601A
 |doi=10.1103/PhysRevLett.110.221601
|pmid=23767711
 |s2cid=20486226
 }}</ref> Scientists found the B<sub>s</sub> meson decaying into two [[muon]]s for the first time, with Large Hadron Collider experiments casting doubt on the scientific theory of [[supersymmetry]].<ref>
{{cite web
 |author=M. Hogenboom
 |date=24 July 2013
 |title=Ultra-rare decay confirmed in LHC
 |url=https://www.bbc.co.uk/news/science-environment-23431797
 |publisher=[[BBC]]
 |accessdate=2013-08-18
}}</ref><ref>{{cite web
 |author=CMS
 |date=14 May 2015
 |title=Mathematical explanation from GENUINE published result
 |url=http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14474.html
 |publisher=Nature
 |accessdate=2015-05-15
}}</ref>

CERN physicist [[Tara Shears]] described the CP violation observations as "verification of the validity of the Standard Model of physics".<ref name="WiredCPViolation">
{{cite magazine
 | author=M. Piesing
 | date=24 April 2013
 | title=Cern physicists observe new difference between matter and antimatter
 | url=https://www.wired.co.uk/news/archive/2013-04/24/cern-antimatter
 | magazine=[[Wired UK]]
 | accessdate=2013-04-24
}}</ref>

== Rare decays ==
The rare decays of the B<sub>s</sub> meson are an important test of the Standard Model.  The branching fraction of the strange b-meson to a pair of muons is very precisely predicted with a value of Br(B<sub>s</sub>→ μ<sup>+</sup>μ<sup>−</sup>)<sub>SM</sub> = (3.66 ± 0.23) × 10<sup>−9</sup>.  Any variation from this rate would indicate possible physics beyond the Standard Model, such as supersymmetry. The first definitive measurement was made from a combination of LHCb and CMS experiment data:<ref>{{Cite journal|title = Observation of the rare Bs0 →μ+μ− decay from the combined analysis of CMS and LHCb data|journal = Nature|date = 4 June 2015|issn = 0028-0836|pages = 68–72|volume = 522|issue = 7554|doi = 10.1038/nature14474|first = C. M. S.|last = Collaboration|arxiv = 1411.4413 |bibcode = 2015Natur.522...68C|pmid=26047778|s2cid = 4394036}}</ref>

<math>Br(B_s \rightarrow \mu^+\mu^-) = 2.8^{+0.7}_{-0.6} \times 10^{-9}</math>

This result is compatible with the Standard Model and set limits on possible extensions.

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

==References==
{{Reflist}}

==External links==
*{{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]]
 |accessdate=2010-01-23
}}

{{Particles}}

{{Use dmy dates|date=August 2019}}

{{DEFAULTSORT:Strange B Meson}}
[[Category:Mesons]]
[[Category:Strange quark]]
[[Category:B physics]]


{{Particle-stub}}