标题： 使用2+1味格点QCD的精密核子电荷与形式因子 显示英文标题

标题： Precision Nucleon Charges and Form Factors Using 2+1-flavor Lattice QCD

摘要： 我们利用七个包含2+1味Wilson-clover费米子的色散系综，给出了同位旋矢量核子电荷和形式因子的高统计结果。 在每个系综上得到的轴向和赝标形式因子，在相关函数的谱分解中包含最低能量的激发态 $N\pi$ 后，满足PCAC关系。 同样地，我们发现 $N\pi\pi $ 激发态对与矢量流相关的相关函数有贡献，这与矢量介子占优模型一致。 由此得出的形式因子与Kelly参数化的实验电学和磁学数据一致。 我们最终估算的同位旋矢量电荷值分别为 $g_{A}^{u-d} = 1.31(06)(05)_{sys}$, $g_{S}^{u-d} = 1.06(10)(06)_{sys}$, 和 $g_{T}^{u-d} = 0.95(05)(02)_{sys}$，其中第一个误差是整体分析不确定性，第二个是额外的综合系统误差。 形式因子得出以下结果：(i) 轴向电荷半径平方，${\langle r_A^2 \rangle}^{u-d}=0.428(53)(30)_{sys}\ {\rm fm}^2$，(ii) 引发的赝标量电荷，$g_P^\ast=7.9(7)(9)_{sys}$，(iii) π-核子耦合常数，$g_{\pi {\rm NN}} = 12.4(1.2)$，(iv) 电荷半径平方，${\langle r_E^2 \rangle}^{u-d} = 0.85(12)(19)_{sys} \ {\rm fm}^2$，(v) 磁矩半径平方，${\langle r_M^2 \rangle}^{u-d} = 0.71(19)(23)_{\rm sys} \ {\rm fm}^2$，以及(vi) 磁矩，$\mu^{u-d} = 4.15(22)(10)_{\rm sys}$。 所有结果均与经验/实验值一致，但误差更大。 最后，我们提出了轴向、电和磁形式因子的Padé参数化，用于 phenomenological 研究的范围是 $0.04< Q^2 <1$ GeV${}^2$。 显示英文摘要

摘要： We present high statistics results for the isovector nucleon charges and form factors using seven ensembles of 2+1-flavor Wilson-clover fermions. The axial and pseudoscalar form factors obtained on each ensemble satisfy the PCAC relation once the lowest energy $N\pi$ excited state is included in the spectral decomposition of the correlation functions used for extracting the ground state matrix elements. Similarly, we find evidence that the $N\pi\pi $ excited state contributes to the correlation functions with the vector current, consistent with the vector meson dominance model. The resulting form factors are consistent with the Kelly parameterization of the experimental electric and magnetic data. Our final estimates for the isovector charges are $g_{A}^{u-d} = 1.31(06)(05)_{sys}$, $g_{S}^{u-d} = 1.06(10)(06)_{sys}$, and $g_{T}^{u-d} = 0.95(05)(02)_{sys}$, where the first error is the overall analysis uncertainty and the second is an additional combined systematic uncertainty. The form factors yield: (i) the axial charge radius squared, ${\langle r_A^2 \rangle}^{u-d}=0.428(53)(30)_{sys}\ {\rm fm}^2$, (ii) the induced pseudoscalar charge, $g_P^\ast=7.9(7)(9)_{sys}$, (iii) the pion-nucleon coupling $g_{\pi {\rm NN}} = 12.4(1.2)$, (iv) the electric charge radius squared, ${\langle r_E^2 \rangle}^{u-d} = 0.85(12)(19)_{sys} \ {\rm fm}^2$, (v) the magnetic charge radius squared, ${\langle r_M^2 \rangle}^{u-d} = 0.71(19)(23)_{\rm sys} \ {\rm fm}^2$, and (vi) the magnetic moment $\mu^{u-d} = 4.15(22)(10)_{\rm sys}$. All our results are consistent with phenomenological/experimental values but with larger errors. Lastly, we present a Pad\'e parameterization of the axial, electric and magnetic form factors over the range $0.04< Q^2 <1$ GeV${}^2$ for phenomenological studies.