INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, MOE Key Laboratory for Particle Physics, Astrophysics and Cosmology, School of Physics and Astronomy, Shanghai Jiao-Tong University, Shanghai 200240, China and Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany.
Phys Rev Lett. 2019 Feb 22;122(7):072001. doi: 10.1103/PhysRevLett.122.072001.
The nucleon sigma term of the isoscalar and isovector quark chromomagnetic dipole moments are essential inputs for the determination of the CP-odd pion-nucleon couplings induced by quark chromoelectric dipole moments. We demonstrate that the former can be mapped to the third moment of the nucleon twist-three chiral-odd distribution functions e^{q}(x) which are in principle measurable in semi-inclusive deep inelastic scattering processes. We perform a survey on existing model calculations as well as experimental data on e^{u}(x)+e^{d}(x) and derive a predicted range for the isoscalar chromomagnetic dipole moment sigma term.
同位旋标量和矢量部分夸克色磁偶极矩的核子 sigma 项是确定由夸克色电偶极矩诱导的 CP 破坏赝矢-核子耦合所必需的重要输入。我们证明，前者可以映射到核子扭量三手征奇分布函数 e^{q}(x)的第三矩上，原则上可以在半单举深度非弹性散射过程中测量到。我们对现有的模型计算以及 e^{u}(x)+e^{d}(x)的实验数据进行了调查，并推导出了同位旋色磁偶极矩 sigma 项的预测范围。
