The Diffractive Dissociation Process at π^-p → π^- (π^-π^+p) 14 GeV/c
<p>We describe an experiment in which a 14 GeV/c π<sup>-</sup> 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...
| Summary: | <p>We describe an experiment in which a 14 GeV/c π<sup>-</sup> 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.</p>
<p>We have studied a sample from this exposure of 4400 events of
the reaction π<sup>-</sup>p → π<sup>-</sup>N* → π<sup>-</sup>π<sup>-</sup>π<sup>+</sup>p. In the two body mass spectra the
only noteworthy feature is the Δ<sup>++</sup>(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<sup>++</sup>(1230) decay
distribution suggests that the Deck mechanism is the major contributor
to the πΔ subchannel.</p>
<p>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.</p> |
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