Speaker
Description
The Gerasimov-Drell-Hearn (GDH) sum rule shows a fundamental relation between real photon absorption and the anomalous magnetic moment to the spin structure of the target. The generalized form of GDH sum rule extends this relation to finite four-momentum transfer squared (Q$^2 > 0$). Jefferson Lab (JLab) experiment E97-110 was carried out with a longitudinally polarized electron beam and transversely and longitudinally polarized $^3$He targets in the experimental Hall A. The experiment measured spin-dependent cross sections for the doubly polarized electron scattering off $^3$He at small scattering angles of 6$^{\circ}$ and 9$^{\circ}$ with beam energies from 1.1 GeV to 4.4 GeV, covering the quasi-elastic region, resonances region, and beyond. The measured cross-sections are used to benchmark the calculations from impulse approximation or Faddeev formalism in the quasi-elastic region. Spin-dependent structure functions ($g_1$ and $g_2$) and their first moments are also extracted at low $Q^2$ from 0.032 to 0.23 GeV$^2$. The experimental results directly investigate the connection between the GDH sum rule at the real-photon point ($Q^2 = 0$) and its extended forms at low $Q^2$, showing a recovering trend at $Q^2 < 0.1$ GeV$^2$. This talk will present the experimental results of JLab E97-110 for the $^3$He target.
