An analysis of the reaction π(^+) N → P Xº at 4 GeV/c

Abstract

This thesis presents en account of the analysis of the reactions π(^+) D → P(_s) P wº and π(^+) D → P(_s) P ηº at 4.0 GeV/c incident momentum, carried out by the author whilst at the University of Durham. The experiment, undertaken in collaboration with the University of Birmingham and the Rutherford Laboratory, is described in detail, particular emphasis being applied to the limitations of the experimental setup, the accuracy of the resulting data and the problems associated with the use of a deuterium target. Following a description of the selection of the channel π(^+) → P(_s) P π (^+) π(^-) π(^o) the production and decay processes of the w(^o) - mesons are analysed in detail. The results are compared with those from previous analyses and with the predictions of various Regge Pole models. To describe the various features of the data it is found necessary to infer the presence of significant contributions from unnatural parity exchanges such as the B - meson, in disagreement with the earlier theoretical interpretations which assumed the complete domination of the natural parity component, namely p - exchange. As part of this analysis the nature of the associated background is determined, and the results indicate the possible breakthrough of events from the 4c channel, π(^+)D → P(_s) P π(^+) π(^-)The characteristics of these events in the 1.0 GeV/c(^2) region of the tripion mass spectrum is investigated, and it is concluded that they may well affect the interpretation of the observed enhancements attributed to the controversial H and A(_1) resonances. Finally the production mechanism of the η - meson is analysed.