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Evidence for a Single-Spin Azimuthal Asymmetry in Semi-inclusive Pion Electroproduction

2000; American Physical Society; Volume: 84; Issue: 18 Linguagem: Inglês

10.1103/physrevlett.84.4047

1092-0145

A. Airapetian, Н. Акопов, M. Amarian, E. C. Aschenauer, H. Avakian, R. Avakian, A. Avetissian, E. Avetissian, B. Bains, C. Baumgarten, M. Beckmann, S. Belostotski, J. Belz, T. Benisch, S. Bernreuther, N. Bianchi, J. Blouw, H. Böttcher, A. Borissov, M. Bouwhuis, J. Brack, S. Brauksiepe, B. Braun, B. Bray, S. Brons, W. Brückner, A. Brüll, E. E. W. Bruins, H. J. Bulten, G. P. Capitani, P. Carter, P. Chumney, E. Cisbani, G.R. Court, P.F. Dalpiaz, E. De Sanctis, D. De Schepper, E. Devitsin, P. K. A. de Witt Huberts, P. Di Nezza, M. Düren, A. Dvoredsky, G. Elbakian, J. Ely, A. Fantoni, A. Fechtchenko, M. Ferstl, K. Fiedler, B. W. Filippone, Horst Fischer, B. Fox, J. Franz, S. Frullani, M.-A. Funk, Y. Gärber, H. Gao, F. Garibaldi, G. Gavrilov, P. Geiger, V. Gharibyan, A. Golendukhin, G. Graw, O. Grebeniouk, P. W. Green, L. G. Greeniaus, C. Großhauser, M. Guidal, A. Gute, V. Gyurjyan, J. Haas, W. Haeberli, J.-O. Hansen, M. Hartig, D. Hasch, O. Häusser, F. H. Heinsius, R. Henderson, M. Henoch, R. Hertenberger, Y. Holler, R. J. Holt, W. Hoprich, H. Ihssen, M. Iodice, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, E. Kinney, A. Kisselev, P. Kitching, Hisao Kobayashi, N. Koch, K. Königsmann, M. Kolstein, H. Kolster, В. А. Коротков, W. Korsch, В. Козлов, L. H. Kramer, V. G. Krivokhijine, M. Kurisuno, G. S. Kyle, W. Lachnit, P. Lenisa, W. Lorenzon, N. C. R. Makins, F. K. Martens, J. W. Martin, F. Masoli, A. Mateos, M. McAndrew, K. McIlhany, R. D. McKeown, F. Meißner, F. Menden, Andreas Metz, N. Meyners, O. Mikloukho, C. A. Miller, M. A. Miller, Richard Milner, A. Most, V. Muccifora, R. Mussa, А. Нагайцев, Y. Naryshkin, A. M. Nathan, F. Neunreither, M. Niczyporuk, W.‐D. Nowak, M. Nupieri, K. Oganessyan, T. G. O’Neill, R. Openshaw, J. Ouyang, B. Owen, V. Papavassiliou, S. F. Pate, M. Pitt, S. Potashov, D. H. Potterveld, G. Rakness, A. Reali, R. Redwine, A. R. Reolon, R. Ristinen, K. Rith, Paolo Rossi, S. Rudnitsky, M. Ruh, D. Ryckbosch, Y. Sakemi, I. Savin, C. Scarlett, A. Schäfer, Friedrich Schmidt, H. W. Schmitt, G. Schnell, K. P. Schüler, A. Schwind, J. Anthony Seibert, T.-A. Shibata, K. Shibatani, T. Shin, V. Shutov, C. Simani, A. Simon, K. Sinram, P. Slavich, M. Spengos, E. Steffens, J. Stenger, J. Stewart, U. Stoesslein, M. Sutter, H. Tallini, S. Taroian, A. Terkulov, Oleg Teryaev, Eric Thomas, B. Tipton, M. Tytgat, G. M. Urciuoli, J. van den Brand, G. van der Steenhoven, J. van den Brand, J. van den Brand, M. C. Vetterli, V. Vikhrov, M. G. Vincter, J. Visser, E. Volk, W. Wander, J. Wendland, S. E. Williamson, T. Wise, K. Woller, S. Yoneyama, H. Zohrabian,

High-Energy Particle Collisions Research

Single-spin asymmetries for semi-inclusive pion production in deep-inelastic scattering have been measured for the first time. A significant target-spin asymmetry of the distribution in the azimuthal angle straight phi of the pion relative to the lepton scattering plane was formed for pi(+) electroproduction on a longitudinally polarized hydrogen target. The corresponding analyzing power in the sinstraight phi moment of the cross section is 0.022+/-0.005+/-0.003. This result can be interpreted as the effect of terms in the cross section involving chiral-odd spin distribution functions in combination with a chiral-odd fragmentation function that is sensitive to the transverse polarization of the fragmenting quark.