Two-pion emission decays of negative parity singly heavy baryons

We investigate two-pion emission decays of singly charmed and bottom baryons, focusing on Q^* (1P) and Q^* (1P) with Q=c (charm) or b (bottom) quarks and JP=1/2^-, 3/2^-, belonging to antisymmetric flavor triplet 3F. Our analysis encompasses both sequential processes, involving intermediate states belonging to symmetric flavor sextet 6F such as Q (1S) and Q^ (1S) respectively with JP=1/2^+, 3/2^+, derived from the chiral quark model, and direct process crucial for comparison with experimental data, whose coupling constants estimated using the chiral-partner scheme. We also incorporate the convolution of the parent particle's mass for the Dalitz plot, enabling a more realistic comparison with experimental data. We scrutinize the Dalitz plots of these negative parity states in light of recent Belle measurements for c (2625) ^+. Our findings support the assignment of c (2625) ^+ as the -mode excitation with JP=3/2^- in the quark model, deduced from the the c invariant mass distribution, and we then give predictions for other cases, including the Q^* decays. The observed asymmetry in the invariant mass distribution underscores the important role of the direct process, reflecting the chiral-partner structure in the heavy baryon sector. It is evident that the presence of the direct process is not significant in the three-body decays unless the S-wave resonance contribution is suppressed. We suggest further experimental verification to test our predictions and get more insights into the structure of heavy baryons.