Year: 2026
Type: preprint
Abstract: We report measurements of spin-dependent electron scattering from a polarized $^3$He target, $\vec{^3\textrm{He}}(\vec{e},e')X$, performed at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The $^3$He spin-dependent virtual-photoabsorption cross sections $σ_{TT}$ and $σ_{LT}$, or equivalently the spin structure functions $g_1$ and $g_2$, and their moments were extracted for $0.032 \leq Q^2 \leq 0.23$~GeV$^2$, with coverage from the two-body breakup threshold through the nucleon-resonance region. The moment $I_1(Q^2)$ reaches a plateau below $Q^2 \simeq 0.1$~GeV$^2$, consistent with the Gerasimov--Drell--Hearn (GDH) expectation, while the moment $I_{TT}(Q^2)$, still dominated by the finite-virtuality breakup response, peaks at $Q^2 \simeq 0.1$~GeV$^2$ and turns toward the expected GDH value. Together, the two moments constitute the first observation of a nucleus approaching its GDH sum-rule value at the real-photon point. The moments $I_2(Q^2)$ and $I_{LT}(Q^2)$ yield, respectively, the lowest-$Q^2$ nuclear test of the Burkhardt--Cottingham sum rule and the first nuclear test of the Schwinger sum rule. Besides testing fundamental sum rules, these data provide stringent benchmarks for ab initio calculations of the spin structure of light nuclei.
Source: arXiv (Cornell University)
Authors: E97-110, Jefferson Lab, Collaboration
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G102163711, G1728142190, G1760870335, G1848180026, G2263355576, G2287611682, G262962599, G2702141073, G2896472831, G2988778103, G498139845, G513797252, Polarized Electron Scattering from Nucleons, G6427981414, G6564173845, G6674091005, G6848031779, G6918803902, G7520763071, G969889393, G993149817
OpenAlex ID: W7204882665