1. Measurements of the proton and deuteron spin structure functionsg1andg2
- Author
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Timothy Chupp, R. Gearhart, S.St. Lorant, Koji Abe, D. Kawall, P. Raines, C. Y. Prescott, H. Fonvieille, F. S. Dietrich, L. S. Rochester, J. P. Chen, D. Crabb, M. Kuriki, Ch. Hyde-Wright, T. Averett, A. Rijllart, J. Clendenin, J. Morgenstern, Donal Day, L. C. Smith, R. C. Minehart, R. Erbacher, Z. E. Meziani, F. Staley, G. Court, B. Zihlmann, R. Prepost, Emil Frlez, J. R. Johnson, P. Grenier, Timothy B. Smith, Y. Roblin, R. Antonov, R. M. Lombard-Nelsen, C. C. Young, Avraham Klein, R. Pitthan, T. J. Liu, Dinko Pocanic, J. S. McCarthy, R. A. Lindgren, F. Suekane, G. G. Petratos, Ingo Sick, J. Fellbaum, J. Button-Shafer, H. Borel, K. A. Griffioen, S. E. Kuhn, K. Witte, John C. Mitchell, A. Feltham, E. W. Hughes, D. Walz, F.R. Wesselmann, P. E. Bosted, Z. M. Szalata, D. Garvey, J. M. Bauer, Y. Terrien, T. L. Usher, B. Raue, S. Hoibraten, Pascal Steiner, D. Zimmermann, Vincent Breton, H. R. Band, O. Rondon, H. Tang, K. P. Coulter, S. E. Rock, J. Gomez, R. G. Arnold, L. M. Stuart, T. Maruyama, D. Reyna, J. A. Dunne, X.K. Maruyama, C. Comptour, M. Daoudi, T. Akagi, M. Spengos, H. Yuta, P.L. Anthony, W. Meyer, G. H. Zapalac, H. Dutz, J. Marroncle, B. Youngman, and James L. White
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,Proton ,Deuterium ,Full data ,Zero (complex analysis) ,Resonance ,Spin structure ,Beam energy - Abstract
Measurements are reported of the proton and deuteron spin structure functions ${g}_{1}^{p}$ and ${g}_{1}^{d}$ at beam energies of 29.1, 16.2, and 9.7 GeV, and ${g}_{2}^{p}$ and ${g}_{2}^{d}$ at a beam energy of 29.1 GeV. The integrals ${\ensuremath{\Gamma}}_{p}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{p}{(x,Q}^{2})dx$ and ${\ensuremath{\Gamma}}_{d}={\ensuremath{\int}}_{0}^{1}{g}_{1}^{d}{(x,Q}^{2})dx$ were evaluated at fixed ${Q}^{2}=3(\mathrm{GeV}{/c)}^{2}$ using the full data set to yield ${\ensuremath{\Gamma}}_{p}=0.132\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.009(\mathrm{syst})$ and ${\ensuremath{\Gamma}}_{d}=0.047\ifmmode\pm\else\textpm\fi{}0.003\ifmmode\pm\else\textpm\fi{}0.006.$ The ${Q}^{2}$ dependence of the ratio ${g}_{1}{/F}_{1}$ was studied and found to be small for ${Q}^{2}g1(\mathrm{GeV}{/c)}^{2}.$ Within experimental precision the ${g}_{2}$ data are well described by the twist-2 contribution, ${g}_{2}^{\mathrm{WW}}.$ Twist-3 matrix elements were extracted and compared to theoretical predictions. The asymmetry ${A}_{2}$ was measured and found to be significantly smaller than the positivity limit $\sqrt{R}$ for both proton and deuteron targets. ${A}_{2}^{p}$ is found to be positive and inconsistent with zero. Measurements of ${g}_{1}$ in the resonance region show strong variations with $x$ and ${Q}^{2},$ consistent with resonant amplitudes extracted from unpolarized data. These data allow us to study the ${Q}^{2}$ dependence of the integrals ${\ensuremath{\Gamma}}_{p}$ and ${\ensuremath{\Gamma}}_{n}$ below the scaling region.
- Published
- 1998
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