Spin correlations in $\vec{p}\vec{p}\to pn{\pi }^{+}$ pion production near threshold

Abstract

A first measurement of longitudinal as well as transverse spin correlation coefficients for the reaction $\vec{p}\vec{p}\to pn{\pi }^{+}$ was made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 325, 350, 375 and 400 MeV beam energy. The spin correlation coefficients $A_{xx}+A_{yy},A_{xx}-A_{yy},A_{zz},A_{xz},$ and the analyzing power $A_y,$ as well as angular distributions for $\sigma ({\theta }_{\pi })$ and the polarization observables $A_{ij}({\theta }_{\pi })$ were extracted. Partial wave cross sections for dominant transition channels were obtained from a partial wave analysis that included the transitions with final state angular momenta of $l\le 1$. The measurements of the $\vec{p}\vec{p}\to pn{\pi }^{+}$ polarization observables are compared with the predictions from the Jülich meson exchange model. The agreement is very good at 325 MeV, but it deteriorates increasingly for the higher energies. At all energies agreement with the model is better than for the reaction $\vec{p}\vec{p}\to pp{\pi }^0$.

Preprint, 21 pp, submitted to Phys. Rev. C. Keywords: Mesons, Polarization, Spin Correlations, Few body systems

References in corpus (6)

• Chiral Three-Nucleon Forces from p-wave Pion Production
• Role of the $\Delta$ isobar in the reaction $NN\to NN\pi$ near threshold
• The N N -> NN pi+ Reaction near Threshold in a Chiral Power Counting Approach
• Polarization phenomena in the reaction NN to NNpi near threshold
• Measurement of Spin Correlation coefficients in \vec p \vec p --> d pi^+
• Spin Correlation Coefficients in pp-->pnpi+ from 325 to 400 MeV

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• Heavy Meson Production in NN Collisions with Polarized Beam and Target -- A new facility for COSY
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• Phase ambiguity of the threshold amplitude in pp -> ppπ^0