Radiative ${\Xi }_b^{-}\to {\Xi }^{-}\gamma$ decay

Abstract

Recently, the LHCb Collaboration performed first search for the rare radiative ${\Xi }_b^{-}\to {\Xi }^{-}\gamma$ decay and put an upper limit, $\mathcal{B}({\Xi }_b^{-}\to {\Xi }^{-}\gamma )<1.3\times 10^{-4}$, 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 ${\Xi }_b^{0(-)}({\Xi }_b^{{}^{\prime }-})$ to ${\Xi }^{0(-)}$ and ${\Sigma }^{0(-)}$ baryons using the form factors calculated from light-cone QCD sum rules in full theory. we obtain $\mathcal{B}({\Xi }_b^{-}\to {\Xi }^{-}\gamma )=1.08_{-0.49}^{+0.63}\times 10^{-5}$, 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.

Comments: 16 Pages and 5 Tables