$B^*_s\rightarrow l^+l^-$ decays in light of recent $B$ anomalies

Abstract

Some of the recent measurements in the neutral current sector $b\rightarrow s l^+l^-$ ($l=e$ or $\mu$) as well as in the charged current sector $b \rightarrow c \tau \bar{\nu}$ show significant deviations from their Standard Model predictions. It has been shown that two different new physics solutions, in the form of vector and/or axial vector, can explain all the anomalies in $b\rightarrow s l^+l^-$ sector. We show that the muon longitudinal polarization asymmetry in $B^*_s\rightarrow \mu^+\,\mu^-$ decay is a good discriminant between the two solutions if it can be measured to a precision of $\sim 10\%$, provided the new physics Wilson coefficients are real. We also investigate the potential impact of $b \rightarrow c \tau \bar{\nu}$ anomalies on $B_s^* \rightarrow \tau^+ \tau^-$ decay. We consider a model where the new physics contributions to these two transitions are strongly correlated. We find that two orders of magnitude enhancement in the branching ratio of $B^*_s\rightarrow \tau^+\,\tau^-$ is allowed by the present $b \rightarrow c \tau \bar{\nu}$ data.