S. Dymov, V. Shmakova, T. Azaryan, S. Barsov, V. Baru, P. Benati, D. Chiladze, A. Dzyuba, R. Engels, M. Gaisser, R. Gebel, K. Grigoryev, P. Goslawski, G. Guidoboni, M. Hartmann, A. Kacharava, V. Kamerdzhiev, A. Khoukaz, V. Komarov, P. Kulessa, A. Kulikov, V. Kurbatov, A. Lehrach, P. Lenisa, V. Lensky, N. Lomidze, B. Lorentz, G. Macharashvili, R. Maier, D. Mchedlishvili, S. Merzliakov, M. Mielke, M. Mikirtychyants, S. Mikirtytchiants, M. Nioradze, D. Oellers, H. Ohm, A. Polyanskiy, M. Papenbrock, D. Prasuhn, F. Rathmann, V. Serdyuk, H. Seyfarth, E. Steffens, H. J. Stein, H. Stockhorst, H. Ströher, M. Tabidze, S. Trusov, D. Tsirkov, Yu. Uzikov, Yu. Valdau, Ch. Weidemann, C. Wilkin, P. Wüstner, Q. J. Ye, M. Zhabitsky, for the ANKE Collaboration
The transverse spin correlations A_{x,x} and A_{y,y} have been measured in the pol{d} pol{p} -> p_spec {pp}_s pi- reaction at COSY-ANKE at 353 MeV per nucleon. Here {pp}_s denotes a proton-proton pair with low excitation energy, which is dominantly in the 1S0 state. By measuring three protons in the final state it was possible to extract events where there was a spectator proton p_spec so that the reaction could be interpreted in terms of quasi-free pol{n} pol{p} -> {pp}_s pi-. The proton analyzing power in this reaction was also deduced from this data set by averaging over the polarization of the deuteron beam. The values of A_y^p were shown to be consistent with a refined analysis of our earlier results obtained with a polarized proton incident on a deuterium target. Taking these data in combination with our earlier measurements of the differential cross sections and analyzing powers in the pol{p} p -> {pp}_s pi^0 reaction, a more robust partial wave decomposition was achieved. Three different acceptable solutions were found and the only way of resolving this ambiguity without further theoretical input would be through a measurement of the mixed spin-correlation parameter A_{x,z}.
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http://arxiv.org/abs/1304.3678
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