Boson Resonance of Mass 980 MeV Decaying intoπ−η

Abstract

An enhancement has been observed in the ${\pi }^{-}\eta$ system at mass 980 ± 10 MeV with width 80 ± 30 MeV. This boson state, denoted by ${\pi }_N\mathrm{}\left(980\right)\mathrm{}$, yields a decay angular distribution having about 10% probability for isotropy. It is produced peripherally in the reaction $K^{-}+p\to {Y_1}^{*+}\mathrm{}\left(1385\right)+{{\pi }_N}^{-}\mathrm{}\left(980\right)\mathrm{}$ at 5.5 GeV/c.