Annihilation type rare radiative $B_{(s)}\to V\gamma$ decays

TL;DR

This paper predicts branching ratios for rare radiative B meson decays involving vector mesons, highlighting the significant impact of photon emission from both B-meson and vector-meson loops within the factorization approximation.

Contribution

It introduces the consideration of photon emission from vector-meson loops in decay rate calculations, which was neglected in previous analyses, improving the accuracy of theoretical predictions.

Findings

Predicted branching ratios for specific decay modes: ~1.5×10^{-7} and ~1.7×10^{-7}

Photon emission from vector-meson loops significantly affects decay rates

Estimated prediction accuracy around 20%

Abstract

We obtain predictions for a number of radiative decays $B_{(s)}\to V\gamma$, $V$ the vector meson, which proceed through the weak-annihilation mechanism. Within the factorization approximation, we take into account the photon emission from the $B$-meson loop and from the vector-meson loop; the latter subprocesses were not considered in the previous analyses but are found to have sizeable impact on the $B_{(s)}\to V\gamma$ decay rate. The highest branching ratios for the weak-annihilation reactions reported here are ${\cal B}(\bar B^0_s\to J/\psi\gamma)=1.5\cdot 10^{-7}$ and ${\cal B}(B^-\to \bar D_s^{*-}\gamma)=1.7\cdot 10^{-7}$, the estimated accuracy of these predictions being at the level of 20\%.