πNNdecay of a possibled′dibaryon in the3P0quark pair creation model

Abstract

We study the pionic decay of a possible dibaryon ${d}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\pi}+NN$ and pion decay of single baryons. The ${}^{3}{P}_{0}$ quark-pair-creation model is used for the definition of the effective quark-pion coupling. All necessary coupling constants and vertex form factors both in the baryonic and dibaryonic sectors are calculated in this model using translationally invariant quark-shell-model configurations. A hypothesis for the mass shift of the ${d}^{\ensuremath{'}}$ in a nuclear medium is discussed in order to explain the position of the resonance peak observed in double-charge exchange reactions in nuclei and the nonobservation (or at least doubtful observations) of the ${d}^{\ensuremath{'}}$ as a free resonance outside of a nuclear medium. In this connection the dependence of the ${d}^{\ensuremath{'}}$ decay width on the ${d}^{\ensuremath{'}}$ mass is calculated for two alternative models of the final-state $\mathrm{NN}$ interaction (one-boson exchange potential and Moscow potential). Off-shell effects in the ${d}^{\ensuremath{'}}$ decay are studied on the basis of an algebraic quark-cluster model technique.