Strong and radiative decays of the low-lying S - and P -wave singly heavy baryons

Abstract

The strong and radiative decays of the low-lying $S$- and $P$-wave $\Lambda_{c(b)}$, $\Sigma_{c(b)}$, $\Xi_{c(b)}$, $\Xi_{c(b)}'$ and $\Omega_{c(b)}$ baryons are systematically studied in a constituent quark model. We find that the radiative decay mode $\Lambda_b^0\gamma$ could be very useful for us to establish the missing neutral states $\Sigma_b^{0}$ and $\Sigma_b^{*0}$. Our calculation shows that most of those missing $\lambda$-mode $P$-wave singly heavy baryons have relatively narrow decay width of less than 30 MeV. Their dominant strong and radiative decay channels can be ideal for searching for their signals in future experiment. Configuration mixings between the $J^P=1/2^-$ states $|^2P_{\lambda} \frac{1}{2}^- \rangle$ and $|^4P_{\lambda} \frac{1}{2}^- \rangle$ of the $\mathbf{6}_F$ multiplet are discussed. The $\Xi_c(2930)^0$ state seems to favor the mixed state $|\Xi_c'~ P_{\lambda}\frac{1}{2}^-\rangle_2$ with $J^P=1/2^-$. The $\Sigma_c(2800)$ resonance may be assigned to $|\Sigma_c~ ^2P_{\lambda} \frac{3}{2}^- \rangle$ with $J^P=3/2^-$ or $|\Sigma_c~ ^4P_{\lambda} \frac{5}{2}^- \rangle$ with $J^P=5/2^-$. In general, the excitations of $|^2P_{\lambda} \frac{3}{2}^- \rangle$ and $|^4P_{\lambda} \frac{5}{2}^- \rangle$ of the $\mathbf{6}_F$ multiplet have similar strong decay properties. In order to to identify them, angular distributions of their decays in either strong decay modes or radiative transitions should be needed.