Interpretation of the newly observed $\Omega_c^0$ resonances

Abstract

We study the charmed and bottomed doubly strange baryons within the heavy-quark-light-diquark framework. The two strange quarks are assumed to lie in $S$ wave and thus their total spin is 1. We calculate the mass spectra of the $S$ and $P$ wave orbitally excited states and find the $\Omega_c^0 (2695)$ and $\Omega_c^0 (2770)$ fit well as the $S$ wave states of charmed doubly strange baryons. The five newly $\Omega_c^0(X)$ resonances observed by the LHCb Collaboration, i.e. $\Omega_c^0(3000)$, $\Omega_c^0(3050)$, $\Omega_c^0(3066)$, $\Omega_c^0(3090)$, and $\Omega_c^0(3119)$, can be interpreted as the $P$ wave orbitally excited states. In heavy quark effective theory, we analyze their decays into the $\Xi^+_c K^-$ and $\Xi_c'^+ K^-$, and point out that decays of the five P-wave $\Omega_c^0$ states into the $\Xi_c^+ K^-$ and $\Xi_c'^+K^-$ are suppressed by either heavy quark symmetry or phase space. The narrowness of the five newly observed $\Omega_c^0(X)$ states can then be naturally interpreted with heavy quark symmetry.