Measurement of the virtual-photon asymmetry A2 and the spin-structure function g2 of the proton

/ Authors

A. Airapetian, N. Akopov, Z. Akopov, E. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetisyan, S. Belostotski, N. Bianchi

and 139 more authors

H. Blok, A. Borissov, J. Bowles, V. Bryzgalov, J. Burns, M. Capiluppi, M. Capiluppi, G. Capitani, E. Cisbani, G. Ciullo, G. Ciullo, M. Contalbrigo, M. Contalbrigo, P. Dalpiaz, P. Dalpiaz, W. Deconinck, R. Leo, L. Nardo, E. Sanctis, M. Diefenthaler, M. Diefenthaler, P. Nezza, M. Düren, M. Ehrenfried, G. Elbakian, F. Ellinghaus, A. Fantoni, L. Felawka, S. Frullani, D. Gabbert, G. Gapienko, V. Gapienko, F. Garibaldi, G. Gavrilov, G. Gavrilov, V. Gharibyan, F. Giordano, F. Giordano, S. Gliske, M. Golembiovskaya, C. Hadjidakis, M. Hartig, D. Hasch, A. Hillenbrand, M. Hoek, Y. Holler, I. Hristova, Y. Imazu, A. Ivanilov, H. Jackson, H. Jo, S. Joosten, R. Kaiser, G. Karyan, T. Keri, T. Keri, E. Kinney, A. Kisselev, V. Korotkov, V. Kozlov, P. Kravchenko, P. Kravchenko, V. Krivokhijine, L. Lagamba, L. Lapiḱas, I. Lehmann, P. Lenisa, P. Lenisa, A. L. Ruiz, W. Lorenzon, B. Ma, D. Mahon, N. Makins, S. Manaenkov, L. Manfré, Y. Mao, B. Mariański, A. Ossa, H. Marukyan, C. A. Miller, Y. Miyachi, A. Movsisyan, V. Muccifora, M. Murray, A. Mussgiller, E. Nappi, Y. Naryshkin, A. Nass, M. Negodaev, W. Nowak, L. Pappalardo, L. Pappalardo, R. Pérez-Benito, A. Petrosyan, P. Reimer, A. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, J. Rubin, J. Rubin, D. Ryckbosch, Y. Salomatin, F. Sanftl, F. Sanftl, A. Schäfer, G. Schnell, K. Schüler, B. Seitz, T. Shibata, V. Shutov, M. Stancari, M. Stancari, M. Statera, M. Statera, E. Steffens, J. Steijger, J. Stewart, F. Stinzing, S. Taroian, A. Terkulov, R. Truty, A. Trzciński, M. Tytgat, A. Vandenbroucke, Y. Haarlem, C. Hulse, D. Veretennikov, V. Vikhrov, I. Vilardi, S. Wang, S. Yaschenko, Z. Ye, S. Yen, V. Zagrebelnyy, D. Zeiler, B. Zihlmann, P. Żupránski

/ Abstract

A measurement of the virtual-photon asymmetry A2(x,Q2) and of the spin-structure function g2(x,Q2) of the proton are presented for the kinematic range 0.004<x<0.9 and 0.18 GeV2<Q2<20 GeV2. The data were collected by the HERMES experiment at the HERA storage ring at DESY while studying inclusive deep-inelastic scattering of 27.6 GeV longitudinally polarized leptons off a transversely polarized hydrogen gas target. The results are consistent with previous experimental data from CERN and SLAC. For the x-range covered, the measured integral of g2(x) converges to the null result of the Burkhardt–Cottingham sum rule. The x2 moment of the twist-3 contribution to g2(x) is found to be compatible with zero.

Journal: The European Physical Journal C

DOI: 10.1140/epjc/s10052-012-1921-5