Neutron spin sum rules and spin polarizabilities at low Q2

Abstract

Jefferson Lab has become one of the premier facilities for the study of nucleon spin structure. In the past decade, several high precision measurements have been performed that have extended our knowledge of the spin-dependent structure functions g 1 (x, Q 2 ) and g 2 (x, Q 2 ) between Q 2 = 0.02 -5 GeV 2 . From the measured nucleon structure functions, spin moments and polarizabilities have been formed. These proceedings will concentrate on recent measurments on the neutron via a polarized 3 He target in the low Q 2 region. In particular, experiment E97-110 was performed in Hall A to study the neutron and 3 He spin structure at four-momentum transfers between 0.02 and 0.3 GeV 2 . This Q 2 range allows us to make a benchmark-check of Chiral Perturbation Theory calculations. Previous results for the spin polarizabilities down to 0.1 GeV 2 have shown surprising disagreement with these calculations. Preliminary results on the first moments of the neutron spin structure functions are presented.