Heavy Baryons and electromagnetic decays

Abstract

In this talk I review the theory of electromagnetic decays of the ground state baryon multiplets with one heavy quark calculated using Heavy Hadron Chiral Perturbation Theory [1]. The M1 and E2 amplitudes for S * → Sγ, S * → Tγ and S → Tγ are separately analyzed. All M1 transitions are calculated up to ???(1/Λ χ 2). The E2 amplitudes contribute at the same order for S * → Sγ, while for S * → Tγ they first appear at ???(1/( m Q Λ χ 2)) and for S → Tγ are completely negligible. Once the loop contributions is considered, relations among different 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 these decay widths. Furthermore, one can obtain an absolute prediction for Γ(Ξ c 0′(*) → Ξ c 0γ) and Γ(Ξ b −′(*) → Ξ b −γ).