Diffraction dissociation of neutrons in the reaction dp --> ppp[pi]- at 25 GeV/c

Abstract

We observe the reaction dp --> pspec (p[pi]-)p in a bubble chamber exposure at 25 GeV/c incident deuteron momentum. The (p[pi]-) system with invariant mass below 2.0 GeV is interpreted as neutron diffraction dissociation. The (p[pi]-) mass spectra show little if any direct evidence of N* production. The decay angular distributions and the momentum transfer distributions of the (p[pi]-) system suggest a smooth increase in contributions from higher partial waves with increased mass or momentum transfer. A simple partial-wave analysis shows a P11 contribution below 1.3 GeV for small -t' and a dominant D13 contribution elsewhere. Both the P11 and D13 amplitudes peak far below the N*(1470) and N*(1520) resonances. We also find evidence for the charge-exchange reaction np --> p(p[pi]-). In this process the (p[pi]-) system shows evidence for [Delta]o(1236) and N*(1520) production.