Electromagnetic decays of heavy baryons - art. no. 094009

The electromagnetic decays of the ground state baryon multiplets with one h eavy quark are calculated using heavy hadron chiral perturbation theory. Th e M1 and E2 amplitudes for S*-->S gamma, S*-->T gamma and S-->T gamma are s eparately computed. All M1 transitions are calculated up to O(1/Lambda(chi) (2)). The E2 amplitudes contribute at the same order for S*-->S gamma, whil e for S*-->T gamma they first appear at O(1/(m(Q)Lambda(chi)(2))) and for S -->T gamma are completely negligible. The renormalization of the chiral loo ps is discussed and relations among different decay amplitudes are derived. We find that chiral loops involving electromagnetic interactions of the li ght pseudoscalar mesons provide a sizable enhancement of these decay widths . Furthermore, we obtain an absolute prediction for Gamma(Xi(c)(o)'((*))--> Xi(c)(o)gamma) and Gamma(Xi(b)(-)'((*))-->Xi(b)(-)gamma). Our results are c ompared to other estimates existing in the literature.