Single-spin azimuthal asymmetry in exclusive electroproduction of pi /sup +/ mesons

Airapetian, A. et al. (2002) Single-spin azimuthal asymmetry in exclusive electroproduction of pi /sup +/ mesons. Physics Letters B, 535(1-4), 85 -92. (doi: 10.1016/S0370-2693(02)01780-X)

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A single-spin asymmetry in the distribution of exclusively produced pi /sup +/ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin phi moment of the polarization asymmetry of the cross section is measured to be -0.18+or-0.05(stat.)+or-0.02(syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing x and increasing -t and vanish at t to t/sub min/ |t|. Further, the data show that the longitudinal target polarization component with respect to the virtual photon direction provides the dominant contribution to the measured asymmetry at small x. A next-to-leading twist calculation would thus be required for a complete description of the measurement. The present data, in combination with future HERMES measurements on a transversely polarized target [18] for which a large asymmetry is expected, opens the way to experimentally disentangle the asymmetry arising from the two target polarization components. This information may provide a first glimpse of certain unknown Generalized Parton Distributions.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Kaiser, Professor Ralf
Authors: Airapetian, A., Akopov, N., Akopov, Z., Amarian, M., Aschenauer, E.C., Avakian, H., Avakian, R., Avetissian, A., Avetissian, E., Bailey, P., Baturin, V., Baumgarten, C., Beckmann, M., Belostotski, S., Bernreuther, S., Bianchi, N., Bottcher, H., Borissov, A., Bouhali, O., Bouwhuis, M., Brack, J., Brauksiepe, S., Brull, A., Brunn, I., Bulten, H.J., Capitani, G.P., Chumney, P., Cisbani, E., Ciullo, G., Court, G.R., Dalpiaz, R., De Leo, R., De Nardo, L., De Sanctis, E., De Schepper, D., Devitsin, E., Witt Huberts, P.K.A., Di Nezza, P., Duren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Ely, J., Fabbri, R., Fantoni, A., Fechtchenko, A., Felawka, L., Filippone, B., Fischer, H., Fox, B., Franz, J., Frullani, S., Garberg, Y., Garibaldi, F., Garutti, E., Gavrilov, G., Gharibyan, V., Graw, G., Grebeniouk, O., Green, P.W., Greeniaus, L.G., Gute, A., Haeberli, W., Hafidi, K., Hartig, M., Hasch, D., Heesbeen, D., Heinsius, F.H., Henoch, M., Hertenberger, R., Hesselink, W.H.A., Hofman, G., Holler, Y., Holt, R.J., Hommez, B., Iarygin, G., Izotov, A., Jackson, H.E., Jgoun, A., Jung, P., Kaiser, R., Kisselev, A., Kitching, P., Konigsmann, K., Kolster, H., Korotkov, V., Kotik, E., Kozlov, V., Krauss, B., Krivokhijine, V.G., Kyle, G., Lagamba, L., Laziev, A., Lenisa, P., Liebing, P., Lindemann, T., Lorenzon, W., Maas, A., Makins, N.C.R., Marukyan, H., Masoli, F., McIlhany, K., Meissner, F., Menden, F., Mexner, V., Meyners, N., Mikloukho, O., Milner, R., Muccifora, V., Nagaitsev, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaeva, K., Nowak, W.D., Oganessyan, K., O'Neill, T.G., Owen, B.R., Pate, S.F., Podiatchev, S., Potashov, S., Potterveld, D.H., Raithel, M., Rakness, G., Rappoport, V., Redwine, R., Reggiani, D., Reimer, P., Reolon, A.R., Rith, K., Robinson, D., Rostomyan, A., Ryckbosch, D., Sakemi, Y., Sanjiev, I., Sato, F., Savin, I., Scarlett, C., Schafer, A., Schill, C., SChmidt, F., Schnell, G., Schuler, K.P., Schwind, A., Seibert, J., Seitz, B., Shibata, T.A., Shutov, V., Simani, M.C., Simon, A., Sinram, K., Steffens, E., Steijger, J.J.M., Stewart, J., Stosslein, U., Suetsugu, K., Taroian, S., Terkulov, A., Tessarin, S., Thomas, E., Tipton, B., Tytgat, M., Urciuoli, G.M., van den Brand, J.F.J., van der Steenhoven, G., de Vyver, R.V., Vetterli, M.C., Vikhrov, V., Vincter, M.G., Visser, J., Volmer, J., Weiskopf, C., Wendland, J., Wilbert, J., Wise, T., Yen, S., Yoneyama, S., and Zohrabian, H.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physics Letters B
Publisher:Elsevier BV
ISSN (Online):1873-2445

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