Analysis of Negative-Pion Photoproduction Near theP33Resonance: Test of theΔI<~1Rule and Time-Reversal Invariance

Abstract

Angular distribution for the reaction ${\pi }^{-}p\to \gamma n$ are analyzed. Existing sets of multipoles do not agree with the data. An acceptable fit is obtained with the Sanda-Shaw model of an electromagnetic current with an isotensor component of $-0.1>x>-0.4\mathrm{}$. The model of Christ and Lee is used to estimate the magnitude of a possible $T$-invariance violation implied by the difference between the data at $\tilde{E}=1245\mathrm{}$ MeV and the inverse reaction deduced from $\gamma d$ work. A strong violation in the isovector or isotensor amplitude is excluded, but a maximum violation in the isoscalar amplitude is possible.