P−pInteractions at 2 Bev. I. Single-Pion Production

Abstract

An analysis of 3600 two-pronged events, obtained in p-p interactions at 2 Bev in the BNL 20-in. hydrogen bubble chamber, was made. Cross sections were measured for elastic scattering, for the two modes of single-pion production, p + p yields p + n + pi /sup +/, p + p yields p + p + pi /sup 0/ and for strange particle production. The branching ratio for the two one pion production reactions is sigma (pn pi /+sup 0/) = 4.17 plus or minus 0.25 Momentum distributions and Q values indicate that singlepion production proceeds almost entirely through the of the extended isobar model and also a one-pion exchange model for production. The branching ratio and momentum distributions can be explained by including a small effect from the I = 1/2 resonant state in addition to the dominant I =3/2 resonance. The c.m. angular distribution of the nucleons in single-pion production shows very marked backward-forward peaking indicating a one-pion exchange mechanism. Absolute differential cross sections as a function of laboratory kinetic energy were calculated from Selleri's equation for the pn pi reaction. There is sgreement with the data for low four-momentum transfers ers the theoretical are larger than the experimentalmore » cross sections. (auth)« less