Properties of single cluster structure of $d^*(2380)$ in chiral SU(3) quark model

Abstract

The structure of $d^*(2380)$ is re-studied with the single cluster structure in the chiral SU(3) quark model which has successfully been employed to explain the scattering and binding behaviors of baryonic systems. The mass and width are explicitly calculated with two types of trial wave functions. The result shows that the $(0s)^6 [6]_{orb}$ configuration is easy to convert to the configuration with the same $[6]_{orb}$ symmetry but $2\hbar \omega$ excitation back and forth, however, it is seldom to turn into a two-cluster configuration with a (1s) relative motion in between. The resultant mass and width are about $2394$MeV and $25$MeV, respectively, and the stable size is about $0.75fm$, which are consistent with both the results in the two-cluster configuration calculation and the data measured by the COSY collaboration. It seems that the observed $d^*$ is a six-quark dominated exotic state with a spherical shape and breath mode in the coordinate space. Moreover, if $d^*$ does have $2\hbar \omega$ excitation, the $d^* \to np\pi\pi\pi$ decay mode might be a good place to distinguish the real structure of the observed phenomenon by COSY. The masses of various isospin-spin states of six-light-quark systems are also computed. It is shown that by considering the coupling with the configurations with $2\hbar \omega$ excitations, only the mirror state with $IS$=$30$ will be lower down to the place where whose mass is slightly higher than the value of the $\Delta\Delta$ threshold.