$B^0_{s} \rightarrow \mu^+\mu^-$ at LHC

TL;DR

This paper reports combined measurements of the rare decays of $B_{s}^0$ and $B^0$ mesons into muon pairs, providing important tests of the Standard Model and potential signs of New Physics.

Contribution

It presents the first combined analysis of CMS and LHCb data on these rare decays, measuring their branching fractions with improved precision.

Findings

Measured $ ext{BR}(B_{s}^0 ightarrow \mu^+\mu^-)$ as (2.8^{+0.7}_{-0.6})×10^{-9}

Measured $ ext{BR}(B^0 ightarrow \\mu^+\\mu^-)$ as (3.9^{+1.6}_{-1.4})×10^{-10}

Significance of 6.2σ for $B_{s}^0$ decay detection

Abstract

Rare leptonic decays of $B_{(s)}^0$ mesons are sensitive probes of New Physics effects. A combination of the CMS and LHCb analyses on the search of the rare decays $B_{s}^0 \rightarrow \mu^+\mu^-$ and $B^0 \rightarrow \mu^+\mu^-$ is presented. The branching fractions of $B_{s}^0 \rightarrow \mu^+\mu^-$ and $B^0 \rightarrow \mu^+\mu^-$ are measured to be $\mathcal{B}(B_{s}^0 \rightarrow \mu^+\mu^-) = (2.8 \,^{+0.7}_{-0.6}) \times 10^{-9}$ and $\mathcal{B}(B^0 \rightarrow \mu^+\mu^-) = (3.9 \,^{+1.6}_{-1.4}) \times 10^{-10}$ respectively. A statistical significances of $6.2\,\sigma$ is evaluated for $B_{s}^0 \rightarrow \mu^+\mu^-$ from the Wilks' theorem while a significance of $3.0\, \sigma$ is measured for $B^0 \rightarrow \mu^+\mu^-$ from the Feldman-Cousins procedure.