HAL : in2p3-00257582, version 1
 arXiv : 0802.2232
 Moments of the Spin Structure Functions $g_1^p$ and $g_1^d$ for 0.05 $< Q^2 < 3.0 GeV^2$
 CLAS Collaboration(s)
 (2008)
 The spin structure functions $g_1$ for the proton and the deuteron have been measured over a wide kinematic range in x and $Q^2$ 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 $Q^2$, 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 $Q^2$.
 Thème(s) : Physique/Physique Nucléaire Expérimentale
 Mot(s)-clé(s) : Spin structure functions – nucleon structure – Chiral Perturbation Theory
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0802.2232
 in2p3-00257582, version 1 http://hal.in2p3.fr/in2p3-00257582 oai:hal.in2p3.fr:in2p3-00257582 Contributeur : Suzanne Robert <> Soumis le : Mardi 19 Février 2008, 16:44:02 Dernière modification le : Mercredi 20 Février 2008, 09:29:38