The reaction $pp\to pp\ddot{I}{€}^0$ near threshold

Abstract

We perform a momentum-space calculation of the reaction $pp\to pp\ddot{I}{€}^0$ near threshold. Direct production and pion rescattering are taken into account. For the latter a T-matrix obtained from a microscopic model of the $\ddot{I}€N$ interaction is employed. The effects of some approximations commonly used in studies of $pp\to pp\ddot{I}{€}^0$ \ are discussed. We find that those approximations overestimate the cross section and also modify its energy dependence. We obtain a significant contribution from rescattering, but not nearly enough to describe the data.