Radiative $\Xi_{b}^{-}\rightarrow \Xi^{-}\gamma$ decay

Abstract

Recently, the LHCb Collaboration performed first search for the rare radiative $\Xi_{b}^{-}\rightarrow \Xi^{-}\gamma$ decay and put an upper limit, ${\cal B}(\Xi_{b}^{-}\to \Xi^{-}\gamma) < 1.3 \times 10^{-4}$, on its branching ratio. The measurement agrees well with existing theory prediction using SU(3) flavor symmetry method, but shows a slight tension with the previous prediction from light-cone sum rules. Inspired by this, we investigate this decay as well as other radiative decays of $\Xi_b^{0(-)}(\Xi^{'-}_{b})$ to $\Xi^{0(-)}$ and $\Sigma^{0(-)}$ baryons using the form factors calculated from light-cone QCD sum rules in full theory. we obtain $ {\cal B}(\Xi_{b}^{-}\to \Xi^{-}\gamma)=1.08^{+0.63}_{-0.49} \times 10^{-5} $, which lies below the upper limit set by LHCb and is consistent with flavor-symmetry driven prediction. Our predictions on other channels may be checked in experiment and by other phenomenological approaches.