Exploring pion emission properties of (strange) hidden-charm molecular pentaquarks in a chiral quark model

TL;DR

This work investigates pion emission from (strange) hidden-charm molecular pentaquarks within a chiral-quark framework incorporating coupled-channel dynamics. By computing decay amplitudes and widths for transitions such as $P_c(4457)\to P_c(4312)+\pi$, $P_c^{\Sigma_c^*\bar{D}^*}\to P_c(4312)+\pi$, $P_c^{\Sigma_c^*\bar{D}^*}\to P_c(4380)+\pi$, and various $P_{cs}^{i}\to P_{cs}^f+\pi$ processes, the study reveals a strong sensitivity of widths to internal wave functions, spin-parity, and available phase space. Coupled-channel effects are shown to be essential, often enhancing or enabling transitions through baryon- or meson-dominated components, with neutral and charged pions exhibiting characteristic relations and interference patterns. The results identify several decay channels with sizable widths (ranging from ~keV to ~hundreds of keV) that can serve as experimental signatures to constrain the structure and quantum numbers of the observed $P_c$ and $P_{cs}$ states and guide searches for additional molecular partners.

Abstract

The internal structure of the exotic $P_c$ and $P_{cs}$ pentaquarks remains an open question. To address this, we demonstrate that pion emission serves as a sensitive probe by calculating its properties within a molecular scenario using the chiral quark model and coupled-channel effects. Our results reveal a strong dependence of the decay widths on the internal structure and spatial wave functions. We therefore expect this study to stimulate experimental measurements of these decays, which are crucial for determining the nature of these states and guiding the search for further molecular partners.

Figures (6)

• Figure 1: The $\pi$ emission process between the $P_c$ molecular states.
• Figure 2: The Jacobi coordinates of the $\Sigma_c\bar{D}^{(*)}$ molecular states.
• Figure 3: Mass positions for possible (strange) hidden-charm molecular states. Here, the mass gaps are in units of MeV.
• Figure 4: The pion emission widths for $\Sigma_c^*\bar{D}^*$ molecules with $I(J^P)=1/2(1/2^-, 3/2^-)$ decaying into $P_c(4312)$.
• Figure 5: The pion emission widths for the $\Sigma_c^*\bar{D}^*$ molecules with $I(J^P)=1/2(1/2^-, 3/2^-, 5/2^-)$ decaying into $P_c(4380)$.