The radiative decays of the singly heavy baryons in chiral perturbation theory

Abstract: In the framework of the heavy baryon chiral perturbation theory (HBChPT), we calculate the radiative decay amplitudes of the singly heavy baryons up to the next-to-next-to-leading order (NNLO). In the numerical analysis, we adopt the heavy quark symmetry to relate some low energy constants (LECs) with those LECs in the calculation of the magnetic moments. We use the results from the lattice QCD simulation as input. With a set of unified LECs, we obtain the numerical (transition) magnetic moments and radiative decay widths. We give the numerical results for the spin-$1\over 2$ sextet to the spin-$1\over 2$ antitriplet up to the next-to-leading order (NLO). The nonvanishing $\Gamma(\Xi_c^{'0} \rightarrow \Xi^0_c\gamma)$ and $\Gamma(\Xi_c^{*0} \rightarrow \Xi^0_c \gamma)$ solely arise from the U-spin symmetry breaking, and do not depend on the lattice QCD inputs up to NLO. We also systematically give the numerical analysis of the magnetic moments of the spin-$1\over 2$, spin-$3\over 2$ sextet and their radiative decay widths up to NNLO. In the heavy quark limit, the radiative decays between the sextet states happen through the magnetic dipole (M1) transitions, while the electric quadrupole (E2) transition does not contribute. We also extend the same analysis to the single bottom baryons.