Calculation of theπ+π−Mass Distribution in the Reactionπ−p→π−π−N*++

Abstract

A one-pion-exchange (OPE) calculation is made of the ${\pi }^{+}{\pi }^{-}$ mass distribution from the ${\pi }^{-}p\to {\pi }^{-}{\pi }^{-}{N}^{*++}$ reaction in order to determine whether the $\sigma$ enhancement at 400 MeV can be understood as a kinematical effect of the OPE production mechanism for $N^{*++}$. The results of the calculations tend to indicate that any structure in the ${\pi }^{+}{\pi }^{-}$ mass spectrum near 400 MeV cannot be explained in this way.