Strange B meson

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The Bs meson, also called the strange B meson, is a short‑lived, neutral particle made of a bottom antiquark and a strange quark. It weighs about 5.37 GeV/c^2 and has a lifetime of roughly 1.47 trillionths of a second. It carries no electric charge and has spin 0.

One interesting feature of the Bs meson is that it can spontaneously switch into its antiparticle and back again. This particle–antiparticle oscillation is a quantum process predicted by the Standard Model, and scientists study it to test the theory.

Researchers measure the oscillation speed, described by a quantity called Δms, which is about 17.8 per picosecond. The first solid evidence for Bs oscillation was reported by Fermilab experiments in 2006.

Bs mesons can decay in several ways, including rare decays into a pair of muons. The probability of the Bs decaying to mu+ mu− is predicted very precisely by the Standard Model—about 3.66 × 10^−9. Experiments at the Large Hadron Collider, including LHCb and CMS, have measured a value around 2.8 × 10^−9, which agrees with the prediction within uncertainties. Because this rare decay is so sensitive to new physics, it’s an important place to look for effects beyond the Standard Model, such as supersymmetry.

In addition to oscillations and rare decays, the Bs meson has provided important confirmations of the Standard Model, including observations of CP violation in its decays. Studying Bs mesons at facilities like Fermilab and the Large Hadron Collider helps physicists test our understanding of fundamental particles and forces.