Study of $B_s\to\ell^+\ell^-\gamma$ decays in covariant quark model

TL;DR

This paper investigates the rare decay processes of B_s mesons into a lepton pair and a photon within the Standard Model, using a covariant quark model to compute form factors and predict branching ratios.

Contribution

It introduces a comprehensive calculation of $B_s o ell ightarrow ext{gamma}$ decay form factors across the full kinematic range within a covariant confined quark model, including analytic decay formulas.

Findings

Predicted branching fractions for $B_s o ell ext{gamma}$ decays.

Form factors behavior across the full kinematic region.

Comparison with other theoretical approaches.

Abstract

We study the rare radiative leptonic decays $B_s\to\ell^+\ell^-\gamma$ ($\ell=e,\mu,\tau$) within the Standard Model, considering both the structure-dependent amplitude and bremsstrahlung. In the framework of the covariant confined quark model developed by us, we calculate the form factors characterizing the $B_s\to\gamma$ transition in the full kinematical region of the dilepton momentum squared and discuss their behavior. We provide the analytic formula for the differential decay distribution and give predictions for the branching fractions in both cases: with and without long-distance contributions. Finally, we compare our results with those obtained in other approaches.