Effects of transversity in deep-inelastic scattering by polarized protons

Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Bacchetta, A.; Belostotski, S.; Bianchi, N.; Blok, H.; Borissov, A.; Bowles, J.; Brodsky, I.; Bryzgalov, V.; Burns, J.; Capiluppi, Marco; Capitani, G.; Cisbani, E.; Ciullo, Giuseppe; Contalbrigo, Marco; Ferretti, Paola; Deconinck, W.; Leo, R. D.; Nardo, L. D.; Sanctis, E. D.; Diefenthaler, M.; Nezza, P. D.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gharibyan, V.; Giordano, Francesca; Gliske, S.; Golembiovskaya, M.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hill, G.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H.; Jo, H.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Kobayashi, N.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Lagamba, L.; Lamb, R.; Lapikás, L.; Lehmann, I.; Lenisa, Paolo; Linden Levy, L.; Ruiz, A. L.; Lorenzon, W.; Lu, X.; Lu, X.; Ma, B.; Mahon, D.; Makins, N.; Manaenkov, S.; Manfré, L.; Mao, Y.; Marianski, B.; de la Ossa, A. M.; Marukyan, H.; Miller, C.; Miyachi, Y.; Movsisyan, A.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.; Pappalardo, Luciano Libero; Perez Benito, R.; Pickert, N.; Raithel, M.; Reimer, P.; Reolon, A.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanftl, F.; Schäfer, A.; Schnell, G.; Seitz, B.; Shibata, T.; Shutov, V.; Stancari, Michelle Dawn; Statera, Marco; Steffens, E.; Steijger, J.; Stenzel, H.; Stewart, J.; Stinzing, F.; Taroian, S.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; der Nat, P. v.; Haarlem, Y. V.; Hulse, C. V.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Vogel, C.; Wang, S.; Yaschenko, S.; Ye, H.; Ye, Z.; Yen, S.; Yu, W.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

doi:10.1016/j.physletb.2010.08.012

Single-spin asymmetries for pions and charged kaons are measured in semi-inclusive deep-inelastic scattering of positrons and electrons off a transversely nuclear-polarized hydrogen target. The dependence of the cross section on the azimuthal angles of the target polarization ([phi]S) and the produced hadron ([phi]) is found to have a substantial sin([phi]+[phi]S) modulation for the production of [pi]+, [pi]- and K+. This Fourier component can be interpreted in terms of non-zero transversity distribution functions and non-zero favored and disfavored Collins fragmentation functions with opposite sign. For [pi]0 and K- production the amplitude of this Fourier component is consistent with zero.