Confirmation of Dip-Bump Structure in Backwardπ−−dElastic Scattering: Possible Evidence for Dibaryon Resonances

Abstract

The backward differential cross section for ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{-}d$ elastic scattering has been measured at incident momenta between 420 and 1160 MeV/c. The data show two bumps at around 670 and 1100 MeV/c, two dips near 630 and 980 MeV/c, and a break at 550 MeV/c. The result of a phenonomenological fit is consistent with the existence of three dibaryon resonances in this energy region. A theoretical calculation of Kanai et al. agrees well with the data below 800 MeV/c, but the agreement becomes worse above 800 MeV/c.