论文标题
在2+1+1-Fravor HISQ晶格上，三叶草费米的核子轴向形式因子因子
Nucleon Axial Form Factors from Clover Fermion on 2+1+1-flavor HISQ Lattice
论文作者
论文摘要
核子轴向形式因子 - 轴向$ g_a $，诱导的伪cal $ \ widetilde {g} _p $和伪ca $ g_p $ - 在晶格QCD计算中显示了大型系统。主要症状是违反了三个形式之间部分保守的轴向电流（PCAC）关系，而与现象学估计值相比，诱导的伪内分偶联$ g_p^\ ast $ $ g_p^\ ast $和轴向电荷半径$ r_A $相比。小$ g_p^\ ast $是Pion-Pole优势（PPD）假设失败的结果，尤其是在低$M_π^2 $时。小充电半径$ r_a $和$ g_a $的低估是相关的。主要的系统负责人是缺乏在对核子两点相关器的多符合拟合中未表现出来的低能（$nπ$）状态。我们表明，可以通过三点相关器$ \ langle n a_4 n \ rangle $确定这种低能状态，并在轴向电流$ a_4 $的时间组件中插入nucleon nate，即，即标记为$ s_ {a4} $ [1]的轴向电流$ a_4 $。包括适合控制激发状态污染（ESC）的低能状态，可为$ g_a $，$ r_a $和$ g_p^\ ast $提供与实验/现象学值一致的结果。但是，系统的不确定性，尤其是在小$ q^2 $的数据中，现在更大了。
The nucleon axial form factors -- axial $G_A$, induced pseudoscalar $\widetilde{G}_P$ and pseudoscalar $G_P$ -- have displayed large systematics in lattice QCD calculations. The major symptoms were the violation of the partially conserved axial current (PCAC) relation between the three form factors, and the underestimation of the induced pseudoscalar coupling $g_P^\ast$ and the axial charge radius $r_A$ compared to phenomenological estimates. The small $g_P^\ast$ was a consequence of the failure of the pion-pole dominance (PPD) hypothesis, especially at low $M_π^2$. The small charge radius $r_A$ and the underestimate of $g_A$ were related. The dominant systematic responsible is the lack of inclusion of low-energy ($N π$) states that are not manifest in the multiexponential fit to the nucleon two-point correlator. We show that this low-energy state can be determined from the three-point correlator $\langle N A_4 N \rangle $ with the insertion of the temporal component of the axial current $A_4$ within the nucleon state, ie, the strategy labeled $S_{A4}$ [1]. Including this low-energy state in fits to control excited-state contamination (ESC) gives results for $g_A$, $r_A$, and $g_P^\ast$ that are consistent with experimental/phenomenological values. However, the systematic uncertainties, especially in data at small $Q^2$, are now much larger.
