Electromagnetic Decays of Heavy Baryons

TL;DR

This paper calculates electromagnetic decay widths of heavy baryons using Heavy Hadron Chiral Perturbation Theory, revealing significant loop effects and providing specific decay predictions for certain charmed and bottom baryons.

Contribution

It offers the first comprehensive calculation of M1 and E2 decay amplitudes for heavy baryons, including loop effects and absolute width predictions.

Findings

Chiral loops significantly enhance decay widths.

Explicit predictions for Xi_c and Xi_b baryon radiative decays.

E2 amplitudes are negligible for some transitions.

Abstract

The electromagnetic decays of the ground state baryon multiplets with one heavy quark are calculated using Heavy Hadron Chiral Perturbation Theory. The M1 and E2 amplitudes for S^{*}--> S gamma, S^{*} --> T gamma and S --> T gamma are separately 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, while 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 loops is discussed and relations among different decay amplitudes are derived. We find that chiral loops involving electromagnetic interactions of the light pseudoscalar mesons provide a sizable enhancement of these decay widths. Furthermore, we obtain an absolute prediction for the widths of Xi^{0'(*)}_c--> Xi^{0}_c gamma and Xi^{-'(*)}_b--> Xi^{-}_b gamma. Our results are compared to other estimates existing in the literature.