Study of polarized proton diffraction dissociation in the reaction p/sub arrow-up/p→pπ+π-p at 11.75 GeV/c

We present angular distributions and, for the first time, single-spin correlations in the diffraction-dissociation reaction p/sub arrow-up/p→pπ+π-p, for small momentum transfers between the polarized beam and the (pπ+π-) system, at 11.75 GeV/c. The only structures seen in our 2 x 106-event sample turn out to be the well-known threshold enhancement in Δπ and the N(1700), which appears to involve both Δπ and N(1520)π. 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