Rare Decays

TL;DR

This paper reviews recent experimental studies of rare B meson decays, highlighting their significance in probing physics beyond the standard model, recent measurements, and the potential for discovering new physics through deviations in decay observables.

Contribution

It summarizes recent experimental results on rare B decays, including measurements of $B_s o\mu^+\mu^-$ and $B o K^*\mu^+\mu^-$, and discusses their implications for new physics models.

Findings

Observation of $B_s o\mu^+\mu^-$ decay consistent with standard model

First effective lifetime measurement of $B_s o\mu^+\mu^-$ by LHCb

Some tensions in decay observables suggest potential deviations from predictions

Abstract

Studies of rare decays play an important role in the search of physics beyond the standard model. New particles may participate in the loop processes and can be probed by seeing any deviations from the standard model predictions. The very rare decay $B_s\to\mu^+\mu^-$ has been observed with the data collected by CMS and LHCb experiments. The signal seen by the ATLAS experiment is less significant but is compatible with the predictions. The measurement itself provides stringent constraints to new physics models. The first effective lifetime measurement with $B_s\to\mu^+\mu^-$ candidates has been carried out by the LHCb experiment. More data are still required to observe the $B^0\to\mu^+\mu^-$ decays. The $B\to K^*\mu^+\mu^-$ decay also proceeds through a flavour changing neutral current process, and is sensitive to the new physics. Extended measurements are carried out for $B\to K^*\mu^+\mu^-$ decays. Most of the classical physics parameters are found to be consistent with the predictions, but tensions do emerge in some of the observables. More data will help to clarify these potential deviations.