Analysis of the semileptonic $B_c\to D_s^*μ^+ μ^-$ decay mode in the effective field theory approach

Abstract

Discrepancies have been noted between experimental measurements and Standard Model predictions for various observables related to the $B\to(K, K^*,ϕ) ll$ processes. Recently, the Belle-II Collaboration observed a $2.8σ$ deviation from Standard Model predictions in the branching ratio of the $B \to K ν_l \bar{ν_l}$ decay mode. In this context, we investigate the exclusive semileptonic $B_c\to D_s^{*}μ^+ μ^-$ decay mode, mediated by $b\to s$ quark level transition, using Effective Field Theory formalism. We perform a global fit to the new parameters using existing experimental data on $b \to s μ^+ μ^-$. We then estimate the branching ratio and other observables such as forward-backward asymmetry, lepton polarisation asymmetry, and the lepton non-universality parameter of the $B_c\to D_s^{(*)}μ^+ μ^-$ process. Although this process has not yet been detected experimentally, we offer predictions and discuss the observables for $B_c\to D_s^{*}μ^+ μ^-$ in both the Standard Model and potential new physics scenarios.