Hoferichter Martin, Kubis Bastian, Ruiz de Elvira Jacobo, Stoffer Peter
Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550, USA.
Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität Bonn, 53115 Bonn, Germany.
Phys Rev Lett. 2019 Mar 29;122(12):122001. doi: 10.1103/PhysRevLett.122.122001.
If physics beyond the standard model enters well above the electroweak scale, its low-energy effects are described by standard model effective field theory. Already, at dimension 6, many operators involve the antisymmetric quark tensor q[over ¯]σ^{μν}q, whose matrix elements are difficult to constrain from experiment, Ward identities, or low-energy theorems, in contrast to the corresponding vector and axial-vector or even scalar and pseudoscalar currents. However, with normalizations determined from lattice QCD, analyticity and unitarity often allow one to predict the momentum dependence in a large kinematic range. Starting from recent results in the meson sector, we extend this method to the nucleon case and, in combination with pole dominance, provide a comprehensive assessment of the current status of the nucleon form factors of the quark tensor.
如果超出标准模型的物理现象出现在远高于电弱标度的能区，其低能效应可由标准模型有效场论来描述。在六维算符的情况下，许多算符涉及反对称夸克张量(\overline{q}\sigma^{\mu\nu}q)，与相应的矢量、轴矢量甚至标量和赝标量流相比，其实矩阵元很难从实验、沃德恒等式或低能定理中得到约束。然而，通过格点量子色动力学确定归一化后，解析性和幺正性通常能让人们预测在很大运动学范围内的动量依赖关系。从介子领域的最新结果出发，我们将此方法扩展到核子情形，并结合极点主导，对夸克张量的核子形状因子的当前状况进行全面评估。
