Branching fraction measurements of the rare $B^0_s\rightarrow\phi\mu^+\mu^-$ and $B^0_s\rightarrow f_2^\prime(1525)\mu^+\mu^-$ decays

TL;DR

This paper reports precise measurements of the branching fractions for rare $B^0_s$ decays involving muon pairs, including the first observation of $B^0_s ightarrow f_2^\prime(1525)\mu^+\mu^-$, with some results deviating from Standard Model predictions.

Contribution

It provides the first observation of the $B^0_s ightarrow f_2^\prime(1525)\mu^+\mu^-$ decay and measures the branching fraction of $B^0_s ightarrow\phi\mu^+\mu^-$ across different $q^2$ regions, highlighting deviations from the Standard Model.

Findings

Branching fraction of $B^0_s ightarrow\phi\mu^+\mu^-$ is below Standard Model predictions in certain $q^2$ regions.

First observation of $B^0_s ightarrow f_2^\prime(1525)\mu^+\mu^-$ decay with nine sigma significance.

Measured branching fractions provide constraints on new physics models.

Abstract

The branching fraction of the rare $B^0_s\rightarrow\phi\mu^+\mu^-$ decay is measured using data collected by the LHCb experiment at center-of-mass energies of $7$, $8$ and $13\,\rm{TeV}$, corresponding to integrated luminosities of $1$, $2$ and $6\,{\rm fb}^{-1}$, respectively. The branching fraction is reported in intervals of $q^2$, the square of the dimuon invariant mass. In the $q^2$ region between $1.1$ and $6.0\,{\rm Ge\kern -0.1em V}^2\!/c^4$, the measurement is found to lie $3.6$ standard deviations below a Standard Model prediction based on a combination of Light Cone Sum Rule and Lattice QCD calculations. In addition, the first observation of the rare $B^0_s\rightarrow f_2^\prime(1525)\mu^+\mu^-$ decay is reported with a statistical significance of nine standard deviations and its branching fraction is determined.