The Diffractive Dissociation Process at π⁻ p → π⁻ (π⁻π⁺p) at 14 GeV/c

Citation

Rosenfeld, Leo C. (1977) The Diffractive Dissociation Process at π⁻ p → π⁻ (π⁻π⁺p) at 14 GeV/c. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/R3K6-AZ62. https://resolver.caltech.edu/CaltechTHESIS:05192017-142437230

Abstract

We describe an experiment in which a 14 GeV/c π^- beam was incident on a hydrogen bubble chamber. Fast forward scattered pions traversed a wire spark chamber spectrometer downstream of the bubble chamber. Events identified as inelastic by the spectrometer induced a trigger of the bubble chamber camera. The film produced contained a heavy enrichment of events of proton diffractive dissociation.

We have studied a sample from this exposure of 4400 events of the reaction π^-p → π^-N* → π^-π^-π⁺p. In the two body mass spectra the only noteworthy feature is the Δ⁺⁺(1230). In the N* mass spectrum we observe enhancements at 1.49 GeV, 1.72 GeV, and 2.0 GeV. For the prominent 1.72 GeV feature we give estimates of the width and cross section as well as evidence favoring a substantial branching fraction to πΔ(1230). We looked for production of N*(1470) followed by decay to πΔ(1230) with negative result. An examination of the Δ⁺⁺(1230) decay distribution suggests that the Deck mechanism is the major contributor to the πΔ subchannel.

We tested the s-channel and t-channel helicity conservation rules. We observed violent conflict with sCHC and mild conflict with tCHC. We also tested for simultaneous validity of tCHC and the Gribov- Morrison rule and found no significant contradiction with this dual hypothesis.

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