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Precise determination of the spin structure function g 1 of the proton, deuteron, and neutron

2007; American Physical Society; Volume: 75; Issue: 1 Linguagem: Inglês

10.1103/physrevd.75.012007

1550-7998

A. Airapetian, Н. Акопов, Z. Akopov, A. Andrus, E. C. Aschenauer, W. Augustyniak, R. Avakian, A. Avetissian, E. Avetissian, S. Belostotski, N. Bianchi, H.P. Blok, H. Böttcher, A. Borissov, A. Borysenko, A. Brüll, V. Bryzgalov, M. Capiluppi, G. P. Capitani, G. Ciullo, M. Contalbrigo, P.F. Dalpiaz, W. Deconinck, R. De Leo, M. Demey, L. De Nardo, E. De Sanctis, E. Devitsin, M. Diefenthaler, P. Di Nezza, J. Dreschler, M. Düren, M. Ehrenfried, A. Elalaoui-Moulay, G. Elbakian, F. Ellinghaus, U. Elschenbroich, R. Fabbri, A. Fantoni, L. Felawka, S. Frullani, A. Funel, D. Gabbert, Y. Gärber, G. Gapienko, В. А. Гапиенко, F. Garibaldi, K. Garrow, G. Gavrilov, V. Gharibyan, F. Giordano, O. Grebeniouk, I. M. Gregor, H. Guler, A. Gute, C. Hadjidakis, M. Hartig, D. Hasch, T. Hasegawa, W.H.A. Hesselink, A. Hillenbrand, M. Hoek, Y. Holler, B. Hommez, I. Hristova, G. Iarygin, A. Ivanilov, A. Izotov, H. E. Jackson, A. Jgoun, R. Kaiser, T. Keri, E. Kinney, A. Kisselev, T. Kobayashi, M. Kopytin, В. А. Коротков, В. Козлов, Bernhard Krauß, P. Kravchenko, V. G. Krivokhijine, L. Lagamba, L. Lapikás, P. Lenisa, P. Liebing, L. A. Linden-Levy, W. Lorenzon, J. Lu, Shichao Lu, B.-Q. Ma, B. Maiheu, N. C. R. Makins, Y. Mao, B. Mariański, H. Marukyan, F. Masoli, V. Mexner, N. Meyners, T. Michler, O. Mikloukho, C. A. Miller, Y. Miyachi, V. Muccifora, M. Murray, А. Нагайцев, E. Nappi, Y. Naryshkin, M. Negodaev, W.‐D. Nowak, H. Ohsuga, A. Osborne, R. Pérez-Benito, N. Pickert, M. Raithel, D. Reggiani, P. E. Reimer, A. Reischl, A. R. Reolon, C. Riedl, K. Rith, G. Rosner, A. Rostomyan, L. Rubáček, J. Rubin, D. Ryckbosch, Y. Salomatin, I. Sanjiev, I. Savin, A. Schäfer, G. Schnell, K. P. Schüler, J. Seele, B. Seitz, C. Shearer, T.-A. Shibata, V. Shutov, K. Sinram, M. Stancari, M. Statera, E. Steffens, J. J. M. Steijger, H. Stenzel, J. Stewart, F. Stinzing, U. Stößlein, J. Streit, P. Tait, Hiroki Tanaka, S. Taroian, B. Tchuiko, A. Terkulov, A. Trzciński, M. Tytgat, A. Vandenbroucke, P. B. van der Nat, G. van der Steenhoven, Y. Van Haarlem, D. Veretennikov, V. Vikhrov, Christian Vogel, Shiqing Wang, C. Weiskopf, Y. Ye, Z. Ye, S. Yen, B. Zihlmann, P. Żuprański,

High-Energy Particle Collisions Research

Precise measurements of the spin structure functions of the proton ${g}_{1}^{p}(x,{Q}^{2})$ and deuteron ${g}_{1}^{d}(x,{Q}^{2})$ are presented over the kinematic range $0.0041\ensuremath{\le}x\ensuremath{\le}0.9$ and $0.18\text{ }\text{ }{\mathrm{GeV}}^{2}\ensuremath{\le}{Q}^{2}\ensuremath{\le}20\text{ }\text{ }{\mathrm{GeV}}^{2}$. The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas targets internal to the HERA storage ring. The neutron spin structure function ${g}_{1}^{n}$ is extracted by combining proton and deuteron data. The integrals of ${g}_{1}^{p,d}$ at ${Q}^{2}=5\text{ }\text{ }{\mathrm{GeV}}^{2}$ are evaluated over the measured $x$ range. Neglecting any possible contribution to the ${g}_{1}^{d}$ integral from the region $x\ensuremath{\le}0.021$, a value of $0.330\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{theo})\ifmmode\pm\else\textpm\fi{}0.025(\mathrm{exp})\ifmmode\pm\else\textpm\fi{}0.028(\mathrm{evol})$ is obtained for the flavor-singlet axial charge ${a}_{0}$ in a leading-twist next-to-next-to-leading-order analysis.