Investigating New Physics through the Observables of Semileptonic $B_{s}\to K^{\ast}(\to K \pi)\mu^{+}\mu^{-}$ Decay

TL;DR

This paper conducts a comprehensive, model-independent analysis of the rare $B_s o K^* o K\pi \mu^+\mu^-$ decay, exploring its potential to reveal new physics beyond the Standard Model through various observables and NP scenarios.

Contribution

It provides the first detailed, model-independent predictions of key observables for this decay, including correlations under new physics Wilson coefficients.

Findings

Notable deviations from SM predictions in multiple observables.

Correlations between observables can constrain NP parameter space.

Decay serves as a promising channel for new physics searches.

Abstract

The rare four-fold decay $B_s \to K^*(\to K\pi)\mu^+\mu^- $, governed by the flavor-changing neutral current transition $b \to d\mu^+\mu^-$, provides a sensitive probe for testing the Standard Model (SM) and investigating signatures of new physics (NP). This work presents a comprehensive model-independent analysis of the decay using the framework of the weak effective field theory. We compute a set of key physical observables, including the differential branching ratio, forward-backward asymmetry, longitudinal polarization fraction, and several normalized angular coefficients $\langle I_i\rangle$, as a function of the dilepton invariant mass squared $q^2$. The impact of NP is explored via both one-dimensional (1D) and two-dimensional (2D) scenarios involving NP Wilson coefficients $C_7^{\text{NP}}$, $C_9^{(\prime)\text{NP}}$, and $C_{10}^{(\prime)\text{NP}}$. Our findings reveal notable deviations from the SM predictions across multiple observables. Furthermore, we analyze the correlations between different observables and their 2D contour plots which would be useful to further constrain the parametric space of possible NP contributions. This study reinforces the potential of $B_s \to K^* \mu^+ \mu^-$ decay as a complementary channel in the search for physics beyond the SM.