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

The decay widths of four-body double-pion decays $\ds\to pn π^0π^0$, $\ds\to pn π^+π^-$, and iso-scalar parts of $\ds\to pp π^0π^-$ and $\ds\to nn π^+π^0$ 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 $ΔΔ$ channel and coupled $ΔΔ$ and $CC$ channel approximations. It is found that in the coupled-channel approximation, the obtained partial decay widths of $\ds\to pn π^0π^0$, $\ds\to pn π^+π^-$, and those of $d^*$ to the iso-scalar parts of $pp π^0π^-$ and $nn π^+π^0$ 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 $ΔΔ$ 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 $ΔΔ$ 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.

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