Reanalysis of rare radiative Ξ_b<SUP>-</SUP> → Ξ<SUP>-</SUP>γ decay in QCD

Abstract

The upper limit of the branching ratio of the rare Xi(-)(b) ->Xi(-)gamma decay is obtained as BRo (Xi(-)(b) ->Xi(-)gamma) < 1.3 x 10(-4) by the LHCb. In the present work we study this decay within the light cone QCD sum rules employing the Xi b distribution amplitudes. At the first stage, the form factors entering the Xi(-)(b) ->Xi(-)gamma decay are obtained. Next, using the results for the form factors the corresponding branching ratio for this decay is estimated to be BR (Xi(-)(b) ->Xi(-)gamma) = (4.8 +/- 1.3)x 10(-5). This value lies below the upper limit established by the LHCb collaboration. Our finding for the branching ratio is also compared with the results of the other theoretical approaches existing in the literature.