First Observation of the Radiative Decay Λ_{b}^{0}→Λγ

Phys Rev Lett. 2019 Jul 19;123(3):031801. doi: 10.1103/PhysRevLett.123.031801.

Abstract

The radiative decay Λ_{b}^{0}→Λγ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of 1.7 fb^{-1} collected by the LHCb experiment at a center-of-mass energy of 13 TeV. Its branching fraction is measured exploiting the B^{0}→K^{*0}γ decay as a normalization mode and is found to be B(Λ_{b}^{0}→Λγ)=(7.1±1.5±0.6±0.7)×10^{-6}, where the quoted uncertainties are statistical, systematic, and systematic from external inputs, respectively. This is the first observation of a radiative decay of a beauty baryon.