Charmed excited baryons with heavy-quark spin symmetry

TL;DR

This paper models recently observed excited charm baryons as molecular states using a unitarized baryon-meson approach that respects chiral and heavy-quark symmetries, matching several experimental states.

Contribution

It introduces a consistent unitarized baryon-meson model incorporating chiral and heavy-quark spin symmetries to describe excited charm baryons as molecular states.

Findings

Identifies three $ ext{Ω}_c$ states with experimental data.

Proposes molecular descriptions for several $ ext{Ξ}_c$ states.

Suggests heavy-quark spin partners among the states.

Abstract

Recently five $\Omega_c$ excited states have been reported by the LHCb Collaboration, four of them corroborated by Belle. The Belle Collaboration has also discovered in 2017 one excited $\Xi_c$ with mass of 2930 MeV. In view of these recent detections, we analyze the possible molecular description of these states, using a unitarized baryon-meson model that incorporates both chiral and heavy-quark spin symmetries in a consistent manner. We pay a special attention to the renormalization procedure, so as to determine the robustness of our predictions. Within our model, we generate dynamically several $\Omega_c$ and $\Xi_c$ states. We find that, at least, three of our $\Omega_c$ states can be identified with the experimental ones and have spin-parity $J=1/2^-$ or $J=3/2^-$. Moreover, we find a plausible molecular description of not only the $\Xi_c(2930)$ state, but also $\Xi_c(2790)$, $\Xi_c(2815)$ and $\Xi_c(2970)$, reported in the PDG. Interestingly, we determine that $\Xi_c(2930)$ and $\Xi_c(2970)$ are heavy-quark spin partners with $J=1/2^-$ and $J=3/2^-$, respectively, while obtaining that $\Xi_c(2930)$, $\Omega_c(3090)$ or the $\Omega_c(3119)$, and $\Sigma_c(2800)$ would belong to the same SU(3) multiplet.