The proton, pion and omega final state produced by 11.7 Gev pions in hydrogen

Abstract

This thesis contains an account of the pwn(^+) final state produced by the interaction of 11.7 GeV/c π(^+) mesons in a hydrogen bubble chamber. 1 event for 4-prong DST = 0.17 µb. The total cross sections for 4-prong 1Cπº events and for the pwπ(^+) final state respectively are 1.31 ± 0.13 mb and 0.134 ± 0.O13 mb. These cross sections vary as a power of incident momentum with exponents of 0.82 and 1.41 respectively. For the reaction π(^+)p → wΛ(^++), values of mass and width of the Δ(^++) and total cross-section σ(π(^+)p → wΔ(^++)) respectively are 1234 ± 8 MeV/c(^2), 122 ± 32 MeV/c(^2) and 53 ± 10 µb. The cross-section decreases with the incident momentum as p(^-n)(_inc) with n = 1,85. The dσ/d|t| and dσ/d|t'| distributions show dips at |t| (or |t'|) = O and = 0.6 (GeV/c)(^2). The slope of the differential cross sections is = 4 GeV(^-2). The predictions on the density matrix elements disagree with the experimental results. There are dips at |t| = O and = 0.5 (GeV/c)(^2) for the natural parity contribution and a dip appears at |t| = 0.2 (GeV/c)(^2) for the unnatural component. Most of the values of the double statistical tensors are compatible with zero. A qualitative theoretical discussion of the results is presented. For the reaction π(^+)p → pB(^+), values of mass, width and total cross-section of the B(+) respectively are 1235 ± 12 MeV/c(^2), 120 ± 48 MeV/c(^2) and 21 ± 6 µb. The cross-section decreases with the incident momentum as p(^-n)(_inc) with n about 1.5. The slope of the differential cross-section is = 4 GeV(^-2). The helicity amplitude for the wº, |f(_o)|(^2) = 0.09 ± 0.07 which disagrees with the prediction of a simple quark model. The values of <J(^2)(_z)> favour J(^P) =1(^+) or 2(^+) but disfavour J = 3 for the B. Assuming J(^P) = 1(^+) assignment, the density matrix elements show that the B(^+) is weakly aligned both in the t- and the s-channel helicity frames. There is no evidence for the production of the higher mass Δ(^++) or higher mesons decaying into wπ(^+) or any resonance decaying into wp.