We study strong and radiative decays of excited singly heavy baryons (SHBs) using an effective chiral Lagrangian based on the diquark picture proposed in Ref. [1]. The effective Lagrangian contains a $U_A(1)$ anomaly term, which induces an inverse mass ordering between strange and nonstrange SHBs with spin-parity $1/2^{-}$. We find that the effect of the $U_A(1)$ anomaly combined with flavor symmetry breaking modifies the Goldberger-Treiman relation for the mass difference between the ground state ${\mathrm{\Lambda }}_Q(1/2^{+})$ and its chiral partner ${\mathrm{\Lambda }}_Q(1/2^{-})$, and ${\mathrm{\Lambda }}_Q(1/2^{-}){\mathrm{\Lambda }}_Q(1/2^{+})\eta$ coupling, which results in suppression of the decay width of ${\mathrm{\Lambda }}_Q(1/2^{-})\to {\mathrm{\Lambda }}_Q(1/2^{+})\eta$. We also investigate the other various decays such as ${\mathrm{\Lambda }}_Q(1/2^{-})\to {\mathrm{\Sigma }}_Q(1/2^{+},3/2^{+})\pi \pi$, ${\mathrm{\Lambda }}_Q(1/2^{-})\to {\mathrm{\Sigma }}_Q(1/2^{+})\pi$, ${\mathrm{\Lambda }}_Q(1/2^{-})\to {\mathrm{\Sigma }}_Q(1/2^{+},3/2^{+})\gamma$, and ${\mathrm{\Lambda }}_Q(1/2^{-})\to {\mathrm{\Lambda }}_Q(1/2^{+}){\pi }^0$ for a wide mass range of ${\mathrm{\Lambda }}_Q(1/2^{-})$.

• Received 22 September 2020
• Accepted 2 November 2020

DOI:https://doi.org/10.1103/PhysRevD.102.114004

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Published by the American Physical Society