The $d^{\ast }$(2380) dibaryon resonance width and decay branching ratios

Abstract

Attempts to reproduce theoretically the relatively small width, $\hat{I}{“}_{d^{\ast }}=80\pm 10$ MeV, of the $I(J^P)=0(3^{+})$ $d^{\ast }$(2380) dibaryon resonance established by the WASA-at-COSY Collaboration are discussed. The validity of associating the $d^{\ast }$(2380) in quark-based models primarily with a tightly bound $\hat{I}”\hat{I}”$ configuration is questioned. The $d^{\ast }$(2380) width and decay branching ratios into $NN\ddot{I}€\ddot{I}€$, $NN\ddot{I}€$ and $NN$ final states are studied within the Gal-Garcilazo hadronic model in which the $d^{\ast }$(2380) is a $\ddot{I}€N\hat{I}”$ resonance embedded in the $NN\ddot{I}€\ddot{I}€$ continuum some 80 MeV below the $\hat{I}”\hat{I}”$ threshold. In particular, predictions are made for the branching ratios of the unobserved yet $d^{\ast }(2380)\to NN\ddot{I}€$ decays which are suppressed in a purely-$\hat{I}”\hat{I}”$ dibaryon model. Comments are also made on a possible connection of the ABC effect observed in the $pn\to d^{\ast }\to d\ddot{I}{€}^0\ddot{I}{€}^0$ resonance reaction to the $d^{\ast }$(2380) dibaryon.

v1 -- 8 pages, 3 figures, 3 tables, submitted for publication; v2 -- one review section removed, 7 pages, 2 figures, 2 tables, Physics Letters B (in press)