Measurement of the virtual-photon asymmetry A(2) and the spin-structure function g(2) of the proton

Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Borissov, A.; Bowles, J.; Bryzgalov, V.; Burns, J.; Capiluppi, Marco; Capitani, G. P.; Cisbani, E.; Ciullo, Giuseppe; Contalbrigo, Marco; Ferretti, Paola; Deconinck, W.; Leo, R. D.; Nardo, L. D.; Sanctis, E. D.; Diefenthaler, M.; Nezza, P. D.; Dueren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Golembiovskaya, M.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H. E.; H. S., Jo; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapikas, L.; Lehmann, I.; Lenisa, Paolo; Ruiz, A. L.; Lorenzon, W.; B. . . Q.,; Mahon, D.; N. C. R.,; Manaenkov, S. I.; Manfre, L.; Mao, Y.; Marianski, B.; A. M., De; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Muccifora, V.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; W. . . D.,; Pappalardo, Luciano Libero; Perez Benito, R.; Petrosyan, A.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanftl, F.; Schaefer, A.; Schnell, G.; Schueler, K. P.; Seitz, B.; T. . . A.,; Shutov, V.; Stancari, Michelle Dawn; Statera, Marco; Steffens, E.; J. J. M.,; Stewart, J.; Stinzing, F.; Taroian, S.; Terkulov, A.; Truty, R.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; Haarlem, Y. V.; Hulse, C. V.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, Z.; Yen, S.; Zagrebelnyy, V.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

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

A measurement of the virtual-photon asymmetry A(2)(x, Q(2)) and of the spin-structure function g(2)(x, Q(2)) of the proton are presented for the kinematic range 0.004 < x < 0.9 and 0.18 GeV2 < Q(2) < 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 g(2)(x) converges to the null result of the Burkhardt-Cottingham sum rule. The x(2) moment of the twist-3 contribution to g(2)(x) is found to be compatible with zero.