Study of Polarized Proton Diffraction Dissociation in the Reaction P

We present angular distributions and, for the first time, single-spin correlations in the diffraction-dissociation reaction p/sub arrow-up/p..-->..p..pi../sup +/..pi../sup -/p, for small momentum transfers between the polarized beam and the (p..pi../sup +/..pi../sup -/) system, at 11.75 GeV/c. The only structures seen in our 2 x 10/sup 6/-event sample turn out to be the well-known threshold enhancement in ..delta pi.. and the N(1700), which appears to involve both ..delta pi.. and N(1520)..pi... The production process exhibits a slope-mass correlation and patterns of helicity nonconservation seen in higher-energy diffractive processes. We also see evidence for a complex helicity structure in the spin correlations. We show that the threshold enhancement is unambiguously S wave in character, while the N(1700) appears to be a mix of states. The overall similarities between our data and those at higher energies, together with the rich structures contained in the angular-distribution correlations (we measure 315 joint moments in each mass and t bin), make our data base highly relevant for theoretical analysis of exclusive diffraction.