The four B mesons (B for bottom- quark ) contain a heavy bottom anti- quark and a light u or d quark, or each of the corresponding antiparticle:
They were discovered in 1983 with the CLEO particle detector at the CESR storage ring at Cornell University in New Jersey (USA). B mesons are currently an object of basic research.
B mesons have a mass of 5.2789 GeV/c2 () or 5.2792 GeV/c2 () and a lifetime of 1.6 × 10-12 seconds.
All B - mesons have approximately equal masses, because the main contribution comes from each heavy b- quark and its antiparticle, and approximately the same decay times because each mainly decays the b- quark into a c- or u-quark. This is relatively slow and can be described by penguin diagrams.
In the system, the mechanism of CP violation is examined (after the CPT theorem is equivalent to the violation of the symmetry against time reversal ), similar to previously in the system of kaons ( the equivalents of the B mesons, if the bottom quark one by one strange- quark replaced).
B mesons containing charm or strangeness
In addition, are called B mesons with charm and strangeness, the mesons, although they include a bottom anti- quark, but instead of an up-or down quarks each have a charm and strange quark, or each the corresponding antiparticle: