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Exclusive ρ 0 electroproduction on transversely polarized protons

2009; Elsevier BV; Volume: 679; Issue: 2 Linguagem: Inglês

10.1016/j.physletb.2009.07.023

1873-2445

A. Airapetian, Н. Акопов, Z. Akopov, E. C. Aschenauer, W. Augustyniak, A. Avetissian, E. Avetisyan, B. Ball, N. Bianchi, H.P. Blok, H. Böttcher, C. Bonomo, A. Borissov, V. Bryzgalov, J. Burns, M. Capiluppi, G. P. Capitani, E. Cisbani, G. Ciullo, M. Contalbrigo, P. Dalpiaz, W. Deconinck, R. De Leo, L. De Nardo, E. De Sanctis, M. Diefenthaler, P. Di Nezza, J. Dreschler, M. Düren, M. Ehrenfried, G. Elbakian, F. Ellinghaus, R. Fabbri, A. Fantoni, L. Fellawka, S. Frullani, D. Gabbert, G. Gapienko, В. А. Гапиенко, V. Gharibyan, F. Giordano, S. Gliske, C. Hadjidakis, M. Hartig, D. Hasch, G. C. Hill, A. Hillenbrand, M. Hoek, Y. Holler, I. Hristova, Y. Imazu, A. Ivanilov, H. E. Jackson, H. S. Jo, S. Joosten, R. Kaiser, T. Keri, E. Kinney, A. Kisselev, B. R. Ko, В. А. Коротков, P. Kravchenko, L. Lagamba, R. Lamb, L. Lapikás, I. Lehmann, P. Lenisa, L. A. Linden-Levy, A. López Ruiz, W. Lorenzon, X.-G. Lu, X. R. Lu, B.-Q. Ma, D. Mahon, N. C. R. Makins, S. I. Manaenkov, L. Manfré, Y. Mao, B. Mariański, A. Martínez de la Ossa, H. Marukyan, C. A. Miller, Y. Miyachi, A. Movsisyan, V. Muccifora, M. Murray, A. Mussgiller, E. Nappi, Y. Naryshkin, A. Nass, W.‐D. Nowak, L. L. Pappalardo, R. Pérez-Benito, P. E. Reimer, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, J. Rubin, D. Ryckbosch, Y. Salomatin, F. Sanftl, A. Schäfer, G. Schnell, K. P. Schüler, B. Seitz, T.-A. Shibata, V. Shutov, M. Stancari, M. Statera, E. Steffens, J. J. M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, S. Taroian, A. Terkulov, A. Trzciński, M. Tytgat, A. Vandenbroucke, P. B. van der Nat, Y. Van Haarlem, C. Van Hulse, M. Varanda, D. Veretennikov, V. Vikhrov, I. Vilardi, Christian Vogel, S. Wang, S. Yaschenko, H. Ye, Z. Ye, S. Yen, W. Yu, D. Zeiler, B. Zihlmann, P. Żuprański,

High-Energy Particle Collisions Research

The exclusive electroproduction of ρ0 mesons was studied with the hermes spectrometer at the Desy laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. Spin density matrix elements for this process were determined from the measured production- and decay-angle distributions of the produced ρ0 mesons. These matrix elements embody information on helicity transfer and the validity of s-channel helicity conservation in the case of a transversely polarized target. From the spin density matrix elements, the leading-twist term in the single-spin asymmetry was calculated separately for longitudinally and transversely polarized ρ0 mesons. Neglecting s-channel helicity changing matrix elements, results for the former can be compared to calculations based on generalized parton distributions, which are sensitive to the contribution of the total angular momentum of the quarks to the proton spin.