Decay width of $d^*(2380)\to NN \pi\pi$ processes

TL;DR

This paper calculates the decay widths of the $d^*(2380)$ resonance into various two-pion nucleon channels using a chiral SU(3) quark model, showing that coupled-channel effects align well with experimental data.

Contribution

It provides a detailed calculation of the $d^*(2380)$ decay widths considering coupled-channel effects, supporting its interpretation as a six-quark exotic state.

Findings

Coupled-channel approximation yields decay widths consistent with experimental data.

Single-channel approximation overestimates decay widths by about a factor of two.

Results support the $d^*(2380)$ as a six-quark dominated exotic resonance.

Abstract

The decay widths of four-body double-pion decays $\ds\to pn \pi^0\pi^0$, $\ds\to pn \pi^+\pi^-$, and iso-scalar parts of $\ds\to pp \pi^0\pi^-$ and $\ds\to nn \pi^+\pi^0$ are explicitly calculated with the help of the $d^*$ wave function obtained in a chiral SU(3) quark model calculation. The effect of the dynamical structure on $\ds$'s width is analyzed both in the single $\Delta\Delta$ channel and coupled $\Delta\Delta$ and $CC$ channel approximations. It is found that in the coupled-channel approximation, the obtained partial decay widths of $\ds\to pn \pi^0\pi^0$, $\ds\to pn \pi^+\pi^-$, and those of $d^*$ to the iso-scalar parts of $pp \pi^0\pi^-$ and $nn \pi^+\pi^0$ are about $7.4$MeV, $16.4$MeV, $3.5$MeV and $3.5$MeV, respectively As a consequence, the total width is about $64.5$MeV. These widths are consistent with those estimated by using the corresponding cross section data in our previous investigation and also the observed data. But in the single $\Delta\Delta$ channel approximation, the widths are still almost 2-times larger than the measured values. Apparently, the explicitly calculated width together with the evaluated mass of $d^*$ in the coupled $\Delta\Delta$ and $CC$ channel approximation can well explain the observed data, which again supports our assertion that the $\ds$ resonance is a six-quark dominated exotic state.