AI 中文总结
该研究在低Q²范围测量³He自旋结构函数及其矩，验证了GDH等求和规则，为轻核自旋结构的从头计算提供严格基准。
AI 中文摘要
我们报告了在托马斯杰斐逊国家加速器装置（Jefferson Lab）上，对极化³He靶进行的自旋依赖电子散射实验测量，即$\boldsymbol{\rightarrow}$³He($\boldsymbol{\rightarrow}$e,e')X。在0.032 ≤ Q² ≤ 0.23 GeV²的范围内，提取了³He自旋依赖的虚光子吸收截面σ_TT和σ_LT，等价于自旋结构函数g₁和g₂及其矩，覆盖范围从两体破裂阈值到核子共振区。矩I₁(Q²)在Q² ≈ 0.1 GeV²以下达到平台，符合Gerasimov-Drell-Hearn（GDH）预期；矩I_TT(Q²)仍由有限虚性破裂响应主导，在Q² ≈ 0.1 GeV²处达到峰值并向预期GDH值转变。这两个矩共同构成了原子核在实光子点趋近其GDH求和规则值的首次观测。矩I₂(Q²)和I_LT(Q²)分别给出了最低Q²下的Burkhardt-Cottingham求和规则核测试，以及首次Schwinger求和规则核测试。除测试基础求和规则外，这些数据为轻核自旋结构的从头计算提供了严格基准。
英文摘要
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.
CommentsCurrent version withdrawn because mistakenly posted before completion of the collaboration review process
