Possibility of dibaryon formation near the N*(1440)N threshold: Reexamination of isoscalar single-pion production

Abstract

The isoscalar single-pion production exhibits a broad bump in the energy dependence of the total cross section, which does not correspond to the usual opening of the ${N}^{*}(1440)$ production channel with subsequent pion decay. We reevaluate the current database and investigate whether the observed bump structure with a width of about 150 MeV points to the formation of dibaryon states with $I({J}^{P})=0({1}^{+})$ and $0({1}^{\ensuremath{-}})$ near the ${N}^{*}(1440)N$ threshold. This situation would be similar to the situation at the $\mathrm{\ensuremath{\Delta}}(1232)N$ threshold, where the signature of a number of dibaryonic resonances has been found.