Angular analyses of $b \to s \mu^+ \mu^-$ transitions at CMS

TL;DR

This paper presents angular analyses of rare B meson decays involving muons at CMS, testing the standard model with results consistent with predictions, and highlighting the importance of future data for more precise tests.

Contribution

The study provides the first detailed angular analysis of $b o s \, \mu^+ \mu^-$ transitions at CMS, including new measurements of angular parameters across different decay channels.

Findings

All measured angular parameters agree with the standard model.

No significant discrepancy observed in the $P_5'$ parameter.

Results support the standard model predictions for these rare decays.

Abstract

The flavour changing neutral current decays can be interesting probes for searching for new physics. Angular distributions of $b \to s \ell^+ \ell^-$ transition processes of both $\mathrm{B}^0 \to \mathrm{K}^{*0} \mu^ +\mu^-$ and $\mathrm{B}^+ \to \mathrm{K}^+ \mu^+\mu^-$ are studied using a sample of proton-proton collisions at $\sqrt{s} = 8~\mathrm{TeV}$ collected with the CMS detector at the LHC, corresponding to an integrated luminosity of $20.5~\mathrm{fb}^{-1}$. Angular analyses are performed to determine $P_1$ and $P_5'$ angular parameters for $\mathrm{B}^0 \to \mathrm{K}^{*0} \mu^ +\mu^-$ and $A_{FB}$ and $F_{H}$ parameters for $\mathrm{B}^+ \to \mathrm{K}^+ \mu^+\mu^-$, all as functions of the dimuon invariant mass squared. The $P_5'$ parameter is of particular interest due to recent measurements that indicate a potential discrepancy with the standard model. All the measurements are consistent with the standard model predictions. Efforts with more channels and more coming data will be continued to further test the standard model in higher precision in future.