Strange quark mass effect in $B_s \to \gamma\gamma,\gamma\ell\bar{\ell}$ decays

TL;DR

This paper analyzes the impact of strange quark mass effects on rare B_s meson decays into photons and leptons, providing new analytic expressions and quantifying the contributions.

Contribution

It introduces a QCD-inspired dispersion approach to calculate next-to-leading power strange quark mass effects, including a previously missed term.

Findings

Strange quark mass contributes about 6% to B_s → γγ decay rate.

The effect is smaller in B_s → γℓℓ decays due to resonance contributions.

New analytic expressions for quark mass effects are derived.

Abstract

In this paper we investigate the next-to-leading power contribution to the $B_s \to \gamma\gamma$ and $B_s \to \gamma\ell\bar{\ell}$ decays from the strange quark mass effect with the dispersion approach which is QCD inspired and more predictive. We have presented the analytic expression of the quark mass contribution in the $B_s \to \gamma\gamma$ and $B_s \to \gamma\ell\bar{\ell}$ decays, together with a new term that is missed in the previous study. The numerical results of the strange quark mass contribution to the $B_s \to \gamma\gamma$ decay is about 6% relative to the total branching ratio, while it is relatively small in the $B_s \to \gamma\ell\bar{\ell}$ decay due to the large resonance contribuiton