C. Bradtke

Experimental determination of the complete spin structure for (p)over-barp -g(Lambda)over-bar Lambda at p((p)over-bar)=1.637 GeV/c

The reaction anti-proton + proton -> anti-Lambda + Lambda -> anti-proton + pi^+ + proton + pi^- has been measured with high statistics at anti-proton beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin target combined with the self-analyzing property of Lambda/anti-Lambda decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of eleven real parameters for each bin of scattering angle, each of these parameters is determined with reasonable precision. From these results all conceivable spin-correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in anti-proton + proton -> anti-Lambda + Lambda near this energy. Existing theoretical models do not give good predictions for those spin-observables that had not been previously measured.

Measurement of spin-transfer observables in pp → ΛΛ at 1. 637 GeV/c

Spin-transfer observables for p p-->Lambda Lambda have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables Dnn and Knn (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of Dnn and Knn presented here are found to be in disagreement with predictions from these models.

Experimental determination of the complete spin structure for anti-proton + proton -> anti-\Lambda + \Lambda at anti-proton beam momentum of 1.637 GeV/c

The reaction anti-proton + proton -> anti-Lambda + Lambda -> anti-proton + pi^+ + proton + pi^- has been measured with high statistics at anti-proton beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin target combined with the self-analyzing property of Lambda/anti-Lambda decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of eleven real parameters for each bin of scattering angle, each of these parameters is determined with reasonable precision. From these results all conceivable spin-correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in anti-proton + proton -> anti-Lambda + Lambda near this energy. Existing theoretical models do not give good predictions for those spin-observables that had not been previously measured.

Experimental determination of the complete spin structure for anti-p p ---> anti-Lambda Lambda at p(anti-p) = 1.637-GeV/c

The reaction anti-proton + proton -> anti-Lambda + Lambda -> anti-proton + pi^+ + proton + pi^- has been measured with high statistics at anti-proton beam momentum of 1.637 GeV/c. The use of a transversely-polarized frozen-spin target combined with the self-analyzing property of Lambda/anti-Lambda decay allows access to unprecedented information on the spin structure of the interaction. The most general spin-scattering matrix can be written in terms of eleven real parameters for each bin of scattering angle, each of these parameters is determined with reasonable precision. From these results all conceivable spin-correlations are determined with inherent self-consistency. Good agreement is found with the few previously existing measurements of spin observables in anti-proton + proton -> anti-Lambda + Lambda near this energy. Existing theoretical models do not give good predictions for those spin-observables that had not been previously measured.

Depolarization and spin transfer in pp→ΛΛ with a polarized target

Abstract The reaction p p → Λ Λ was examined by LEAR experiment PS185/3 at 1.525 and 1.640 GeV/c. The proton target was transversely polarized in order to measure the depolarization and spin transfer. Theoretical calculations of Dnn, the component of the depolarization normal to the production plane, differ greatly according to whether quark-gluon or meson-exchange models are employed. The measured Dnn and spin transfer Knn appear to be inconsistent with the specific models cited.

Measurement of spin-transfer observables in p p-->Lambda Lambda at 1.637 GeV/c.

Spin-transfer observables for p p-->Lambda Lambda have been measured using a transversely polarized frozen-spin target and a beam momentum of 1.637 GeV/c. Current models of the reaction near threshold are in good agreement with existing measurements performed with unpolarized particles in the initial state but produce conflicting predictions for the spin-transfer observables Dnn and Knn (the normal-to-normal depolarization and polarization transfer), which are measurable only with polarized target or beam. Measurements of Dnn and Knn presented here are found to be in disagreement with predictions from these models.