Measurement of the generalized spin polarizabilities of the neutron in the low-Q2 region
Measurement of the generalized spin polarizabilities of the neutron in the low-Q2 region
复制标题
低 Q2 区域中子广义自旋极化率的测量
DOI：
10.1038/s41567-021-01245-9
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发表时间：
2021
期刊：
影响因子：
19.6
通讯作者：
Beck, Arie
中科院分区：
文献类型：
--
作者：
Sulkosky, Vincent;Peng, Chao;Chen, Jian-ping;Deur, Alexandre;Abrahamyan, Sergey;Aniol, Konrad A.;Armstrong, David S.;Averett, Todd;Bailey, Stephen J.;Beck, Arie
在强相互作用变得真正强的区域中理解核子自旋结构对实验和理论都提出了挑战。在低于核子质量约1 GeV的能量标度下，核子内部夸克和胶子之间的强烈相互作用使它们高度相关。它们的相干行为导致有效自由度的出现，需要应用非微扰技术，如手征有效场论。在这里，我们提出了测量中子的广义自旋极化率，量化电磁场下的中子的自旋进动在非常低的能量动量转移平方下降到0.035 GeV 2。在此制度下，手征有效场理论计算，-预计将是适用的。然而，我们的数据显示出与这些预测的强烈差异，对目前中子自旋性质的描述提出了挑战。
Understanding the nucleon spin structure in the regime where the strong interaction becomes truly strong poses a challenge to both experiment and theory. At energy scales below the nucleon mass of about 1 GeV, the intense interaction among the quarks and gluons inside the nucleon makes them highly correlated. Their coherent behaviour causes the emergence of effective degrees of freedom, requiring the application of non-perturbative techniques such as chiral effective field theory. Here we present measurements of the neutron’s generalized spin polarizabilities that quantify the neutron’s spin precession under electromagnetic fields at very low energy-momentum transfer squared down to 0.035 GeV2. In this regime, chiral effective field theory calculations, –are expected to be applicable. Our data, however, show a strong discrepancy with these predictions, presenting a challenge to the current description of the neutron’s spin properties.