Moments of the Spin Structure Functions g1p and g1d for 0.05 < Q2 < 3.0 GeV2

• Published in: Physics letters. B 2009-02, Vol.672
• Main Authors: Bosted, Peter, Burkert, Volker, Deur, Alexandre, Kuhn, Sebastian, Minehart, Ralph, Amaryan, Moscov, Anghinolfi, Marco, Audit, Gerard, Baillie, Nathan, Ball, Jacques, Battaglieri, Marco, Beard, Kevin, Bedlinskiy, Ivan, Berman, Barry, Biselli, Angela, Boyarinov, Sergey, Branford, Derek, Brooks, William, Careccia, Sharon, Carman, Daniel, Casey, Liam, Cazes, Antoine, Cole, Philip, Crede, Volker, Cummings, John, Dashyan, Natalya, Denizli, Haluk, Dennis, Lawrence, Dhuga, Kalvir, Djalali, Chaden, Dugger, Michael, Dytman, Steven, Dzyubak, Oleksandr, Egiyan, Kim, Elouadrhiri, Latifa, Fatemi, Renee, Garcon, Michel, Gevorgyan, Nerses, Girod, Francois-Xavier, Golovach, Evgeny, Guo, Lei, Gyurjyan, Vardan, Hadjidakis, Cynthia, Hakobyan, Hayk, Hanretty, Charles, Holtrop, Maurik, Ireland, David, Isupov, Evgeny, Ito, Mark, Jenkins, David, Kalantarians, Narbe, Khandaker, Mahbubul, Klein, Franz, Kramer, Laird, Kubarovsky, Valery, Kuleshov, Sergey, Lawrence, Dave, Lima, Ana, Lu, Haiyun, Lukashin, K, MacCormick, Marion, Markov, Nikolai, Mattione, Paul, McKinnon, Bryan, Mecking, Bernhard, Mestayer, Mac, Mibe, Tsutomu, Mokeev, Viktor, Moriya, Kei, Nadel-Turonski, Pawel, Niccolai, Silvia, Niculescu, Maria-Ioana, Niczyporuk, Bogdan, O'Rielly, Grant, Osipenko, Mikhail, Park, Kijun, Pasyuk, Evgueni, Paterson, Craig, Pivnyuk, Nikolay, Pogorelko, Oleg, Popa, Iulian, Preedom, Barry, Price, John, Protopopescu, Dan, Ritchie, Barry, Rossi, Patrizia, Rowntree, David, Rubin, Philip, Sabatie, Franck, Schumacher, Reinhard, Seely, Mikell, Sharabian, Youri, Sharov, Dmitri, Shvedunov, Nikolay, Skabelin, Alexander, Stepanyan, Stepan, Stoler, Paul, Strauch, Steffen, Suleiman, Riad, V
• Format: Article
• Language: English
• Subjects: DEUTERONS; ELECTRONS; PERTURBATION THEORY; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; POLARIZABILITY; PROTONS; SPIN; STRUCTURE FUNCTIONS; SUM RULES; TARGETS
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2008.12.063

The spin structure functions $g_1$ for the proton and the deuteron have been measured over a wide kinematic range in $x$ and \Q2 using 1.6 and 5.7 GeV longitudinally polarized electrons incident upon polarized NH$_3$ and ND$_3$ targets at Jefferson Lab. Scattered electrons were detected in the CEBAF Large Acceptance Spectrometer, for $0.05 < Q^2 < 5 $\ GeV$^2$ and $W < 3$ GeV. The first moments of $g_1$ for the proton and deuteron are presented -- both have a negative slope at low \Q2, as predicted by the extended Gerasimov-Drell-Hearn sum rule. The first result for the generalized forward spin polarizability of the proton $\gamma_0^p$ is also reported, and shows evidence of scaling above $Q^2$ = 1.5 GeV$^2$. Although the first moments of $g_1$ are consistent with Chiral Perturbation Theory (\ChPT) calculations up to approximately $Q^2 = 0.06$ GeV$^2$, a significant discrepancy is observed between the $\gamma_0^p$ data and \ChPT\ for $\gamma_0^p$,even at the lowest \Q2.