New physics effects in semileptonic $\bar{B_s} \to K^{*+}(\to K\pi) \ell^- \bar{\nu}_\ell$ decay

TL;DR

This paper investigates potential new physics contributions to the semileptonic decay of B_s mesons into K* mesons and leptons, analyzing how various Lorentz structures could alter observable decay distributions.

Contribution

It introduces a comprehensive effective field theory analysis of new physics effects in B_s to K* decays, considering vector, scalar, and tensor interactions beyond the Standard Model.

Findings

Constraints on new physics parameters from experimental data

Alterations in differential branching fractions and angular observables

Potential signatures of new physics in decay asymmetries

Abstract

We analyze the new physics effects in semileptonic $\bar{B_s} \to K^{*+}(\to K\pi) \ell^- \bar{\nu}_\ell$ decay induced by the $b \to u \ell \nu_{\ell}$ quark level transition. We consider the vector, scalar and tensor new physics Lorentz structures in addition to the SM in effective field theory approach. Constraints on new physics parameters are obtained from experimental observations of both semileptonic and leptonic decays of $B$ mesons, which are governed by the underlyng $b \to u \ell \nu_\ell$ transition. We explore the new physics effects in differential branching fraction, lepton forward-backward asymmetry, fraction of longitudinal polarization of $K^*$ meson and normalized angular observables in $\bar{B_s} \to K^{*+}(\to K\pi) \ell^- \bar{\nu}_\ell$ decay.