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Concept
Méson B
Résumé
In particle physics, B mesons are mesons composed of a bottom antiquark and either an up (_B+), down (_B0), strange (_Strange B0) or charm quark (_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, which is something else entirely.
Each B meson has an antiparticle that is composed of a bottom quark and an up (_B-), down (_AntiB0), strange (_Strange antiB0) or charm (_Charmed b-) antiquark respectively.
_B–_AntiB oscillation
The neutral B mesons, _B0 and _Strange B0, spontaneously transform into their own antiparticles and back. This phenomenon is called 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 _B0–_AntiB0 system to be about 0.496 / picoseconds, and in the _Strange b0–_Strange antib0 system to be Δms = 17.77 ± 0.10 (stat) ± 0.07 (syst) / picosecond measured by CDF experiment at Fermilab. A first estimation of the lower and upper limit of the _Strange b0–_Strange antib0 system value have been made by the DØ experiment also at Fermilab.
On 25 September 2006, Fermilab announced that they had claimed discovery of previously-only-theorized Bs meson oscillation. According to Fermilab's press release:
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.
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