Search

A study of elastic scattering, one-pion production and annihilation reactions in pp interactions at 5.7 GeV/c was carried out, from the two-prong events, obtained in the hydrogen bubble chamber exposed at CERN. Single particle distributions for the reactions pp → ppπ0, pp → pnπ+ and pp → pnπ− are presented. The study of the squared momentum transfer distributions with and without charge exchange in the cross channel shows different behavior of the slope parameters versus the mass of the produced (Nπ) system. The cross sections for isobar production and for diffractive dissociation in the one-pion production reactions are obtained from a detailed Dalitz plot analysis. The results of the analysis of the decay angular distributions for the N(1510) and for the N(1680) produced in these reactions are in agreement with J = 32 and J = 52 assignment, respectively. The cross sections of the annihilation reactions pp → π+π− and pp → π+π−π0 are determined. Finally, we give some as aspects of the mass distributions for the last reaction.

A new method of obtaining an experimental lower bound on the r.m.s. impact parameter of an exclusive process is applied to data on pp → ppπ+π− at 7–25 and 205 GeV/c and on π−p → π−pπ+π− at 16 and 205 GeV/c. The overall lower bounds are compared with geometrical and multiperipheral model predictions, and are shown to rule out the version of the geometrical model in which these processes become central at high energies. Our results for diffractive regions of longitudinal phase space favour a peripheral impact parameter profile for inelastic diffraction. In a related study of transverse momentum correlations in these processes, we find a predominance of “nearest-neighbour” correlations between transverse momentum transfers.