Proton Spin Structure in the Resonance Region

RSS Collaboration; Wesselmann, F. R.; Slifer, K.; Tajima, S.; Aghalaryan, A.; Ahmidouch, A.; Asaturyan, R.; Bloch, F.; Boeglin, W.; Bosted, P.; Carasco, C.; Carlini, R.; Cha, J.; Chen, J. P.; Christy, M. E.; Cole, L.; Coman, L.; Crabb, D.; Danagoulian, S.; Day, D.; Dunne, J.; Elaasar, M.; Ent, R.; Fenker, H.; Frlez, E.; Gan, L.; Gaskell, D.; Gomez, J.; Hu, B.; Jones, M. K.; Jourdan, J.; Keith, C.; Keppel, C. E.; Khandaker, M.; Klein, A.; Kramer, L.; Liang, Y.; Lichtenstadt, J.; Lindgren, R.; Mack, D.; McKee, P.; McNulty, D.; Meekins, D.; Mkrtchyan, H.; Nasseripour, R.; Niculescu, I.; Normand, K.; Norum, B.; Pocanic, D.; Prok, Y.; Raue, B.; Reinhold, J.; Roche, J.; Rohe, D.; Rondon, O. A.; Savvinov, N.; Sawatzky, B.; Seely, M.; Sick, I.; Smith, C.; Smith, G.; Stepanyan, S.; Tang, L.; Testa, G.; Vulcan, W.; Wang, K.; Warren, G.; Wood, S.; Yan, C.; Yuan, L.; Yun, J.; Zeier, M.; Zhu, H.

Proton Spin Structure in the Resonance Region

Authors

Description

We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV < W < 1.910 GeV) at an average four momentum transfer of Q^2 = 1.3 GeV^2. Using the Jefferson Lab polarized electron beam, a spectrometer, and a polarized solid target, we measured the asymmetries A_parallel and A_perp to high precision, and extracted the asymmetries A_1 and A_2, and the spin structure functions g_1 and g_2. We found a notably non-zero A_perp, significant contributions from higher-twist effects, and only weak support for polarized quark--hadron duality.
6 pages, 4 figures, REVTeX4, similar to PRL submission, plots colorized and appenix added, v3: minor edit, matches PRL