Left-Right Asymmetry in Inverseπ−Photoproduction from a Transversely Polarized Proton Target

Abstract

Accurate measurements of the left-right asymmetry in ${\pi }^{-}p\to \gamma n$ at $p_{\pi }=427-625\mathrm{}$ MeV/c with a transversely polarized target are reported. Results are compared with the predictions from the Arai and Fujii single-pion photoproduction partial-wave analysis and with data on the inverse process measured with a deuterium target. The agreement is poor, casting doubt on the correctness of the value for the radiative-decay amplitude of the neutral Roper resonance now in use.