Study of the reaction p

Abstract

We present density-matrix elements and single-spin correlations for the reaction ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}p${\ensuremath{\pi}}^{+}$n at 3, 4, 6, and 11.75 GeV/c, using both longitudinal and transverse beam polarizations. For small momentum transfers, the spin correlations are mainly due to off-shell ${\ensuremath{\pi}}^{+}$p elastic scattering, while for larger t there are large polarization effects associated with the production dynamics for ${p}_{\ensuremath{\uparrow}}$p\ensuremath{\rightarrow}${\ensuremath{\Delta}}^{++}$n. Comparison of longitudinal and transverse polarization correlations suggests that the ${\ensuremath{\Delta}}^{++}$-production spin effects are due mainly to unnatural-parity exchanges. We present a model-dependent amplitude analysis, and extract the energy dependence of the natural- and unnatural-parity-exchange contributions.