Novel nonperturbative approach for radiative $\bar{B}^0(\bar{B}^0_s)\rightarrow J/\psi \gamma$ decays

TL;DR

This paper introduces a new nonperturbative method using a vector meson dominance model to estimate the branching ratios of radiative B meson decays, addressing previous theoretical uncertainties and aligning with experimental bounds.

Contribution

It presents a novel nonperturbative approach based on a recently proposed model and vector meson dominance to predict decay rates of $ar{B}^0$ and $ar{B}_s^0$ to $J/ u ho$ and $ ho ightarrow J/ u ho$ decays.

Findings

Predicted branching ratio for $ar{B}^0 ightarrow J/ u ho$ is approximately 3.5×10^{-8}.

Predicted branching ratio for $ar{B}_s^0 ightarrow J/ u ho$ is approximately 7.2×10^{-7}.

Results are consistent with current experimental upper bounds.

Abstract

Radiative $\bar{B}^0(\bar{B}^0_s)\rightarrow J/\psi \gamma$ decays provide an interesting case to test our understanding of (non)perturbative QCD and eventually to probe physics beyond the standard model. Recently, the LHCb Collaboration has reported an upper bound, updating the results of the BABAR Collaboration. Previous theoretical predictions based on QCD factorization or perturbative QCD have shown large variations due to different treatment of nonfactorizable contributions and meson-photon transitions. In this paper, we report on a novel approach to estimate the decay rates, which is based on a recently proposed model for $B$ decays and the vector meson dominance hypothesis, widely tested in the relevant energy regions. The predicted branching ratios are $\mathrm{Br}[\bar{B}^0\rightarrow J/\psi\gamma]=\left(3.50\pm0.34^{+1.12}_{-0.63}\right)\times10^{-8}$ and $\mathrm{Br}[\bar{B}^0_s\rightarrow J/\psi\gamma]=\left(7.20\pm0.68^{+2.31}_{-1.30}\right)\times10^{-7}$. The first uncertainty is systematic and the second is statistical, originating from the experimental $\bar{B}^0_s\rightarrow J/\psi \phi$ branching ratio.