We present density-matrix elements and single-spin correlations for the reaction p↑p→pπ+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 π+p elastic scattering, while for larger t there are large polarization effects associated with the production dynamics for p↑p→Δ++n. Comparison of longitudinal and transverse polarization correlations suggests that the Δ++-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.
Unpolarized cross sections.
Unpolarized cross sections.
Unpolarized cross sections.
Left-right asymmetries from a deuterium target in a polarized-proton beam were observed with the Argonne National Laboratory effective-mass spectrometer. Results were obtained for both pp and pn elastic scattering from −t=0.15 to 1.0 GeV2 at 2, 3, 4, and 6 GeV/c. For −t≲0.6 GeV2 the pn polarization was found to have the same sign as for pp, but with faster energy dependence, the ratio P(pn)P(pp) at −t=0.3 GeV2 falling from 0.78±0.02 at 2 GeV/c to 0.22±0.03 at 6 GeV/c.
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