Toward establishing the low-lying $P$-wave excited $Σ_c$ baryon states

In this study, by combining the equal spacing rule with recent observations of $Ω_c(X)$ and $Ξ_c(X)$ baryons, we predict the spectrum of the low-lying $λ$-mode $1P$-wave excited $Σ_c$ states. Furthermore, their strong decay properties are predicted using the chiral quark model and the nature of $Σ_c(2800)$ is investigated by analyzing the $Λ_cπ$ invariant mass spectrum. The $Σ_c(2800)$ structure observed in the $Λ_c π$ mass spectrum was found to potentially arise from two overlapping $P$-wave $Σ_c$ resonances, $Σ_c(2813)3/2^-$ and $Σ_c(2840)5/2^-$. These resonances have similar decay widths of $Γ\sim 40$ MeV and predominantly decay into the $Λ_c π$ channel. The $Σ_c(2755)1/2^-$ state is likely to be a very narrow state with a width of $Γ\sim 15$ MeV, with its decays almost saturated by the $Λ_c π$ channel. Additionally, evidence of the $Σ_c(2755)\frac{1}{2}^-$ resonance as a very narrow peak may be seen in the $Λ_cπ$ invariant mass spectrum. The other two $P$-wave states, $Σ_c(2746)\frac{1}{2}^-$ and $Σ_c(2796)\frac{3}{2}^-$, are relatively narrow states with similar widths of $Γ\sim 30$ MeV and predominantly decay into $Σ_cπ$ and $Σ^{*}_cπ$, respectively. We hope our study can provide useful references for discovering these low-lying $P$-wave states in forthcoming experiments.

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