Heavy baryons and electromagnetic decays

In this talk I review the theory of electromagnetic decays of the ground st ate baryon multiplets with one heavy quark calculated using Heavy Hadron Ch iral Perturbation Theory [1]. The M1 and E2 amplitudes for S* --> S gamma, S* --> T gamma and S --> T gamma are separately analyzed. All M1 transition s are calculated up to O(1/Lambda (2)(chi)). The E2 amplitudes contribute a t the same order for S* --> S gamma, while for S* --> T gamma they first ap pear at O(1/(m(Q)Lambda (2)(chi))) and for S* --> T gamma are completely ne gligible. Once the loop contributions is considered, relations among differ ent decay amplitudes are derived. In ref. [1] it is shown that the coupling of the photon to light mesons is responsible of a sizable enhancement of t hese decay widths. Furthermore, one can obtain an absolute prediction for G amma(Theta (0)(c)'((*)) --> Theta (0)(c)gamma) and Gamma(Theta (-)(b)'((*)) --> Theta (-)(b)gamma).