Gluon parton distribution of the nucleon from ( 2+1+1 )-flavor lattice QCD in the physical-continuum limit
Gluon parton distribution of the nucleon from ( 2+1+1 )-flavor lattice QCD in the physical-continuum limit
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DOI：
10.1103/physrevd.108.014508
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发表时间：
2022-10
影响因子：
5
通讯作者：
Zhouyou Fan;W. Good;Huey-Wen Lin
中科院分区：
文献类型：
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作者：
Zhouyou Fan;W. Good;Huey-Wen Lin
我们使用伪 PDF 方法，在由 MILC 协作生成的具有高度改进的交错夸克 (HISQ) 的 $2+1+1$ 风格的晶格系综上，提出了来自晶格 QCD 的第一个物理连续极限 $x$ 依赖的核子胶子分布。我们使用三叶草费米子对三个晶格间距 $a \approx 0.9$、0.12 和 0.15~fm 以及三个 pion 质量 $M_\pi \approx 220$、310 和 690~MeV 进行价态作用，核子两点测量数量高达 $O(10^6)$，核子升压动量高达 3~GeV。我们研究了从晶格计算中获得的简化伪 ITD 矩阵元素的晶格间距和π介子质量依赖性，然后在提取 $xg(x)/\langle x \rangle_g$ 之前将它们外推到连续物理极限。我们使用从相同系综计算出的胶子动量分数 $\langle x \rangle_g$ 来首次完全通过晶格 QCD 模拟来确定核子胶子非极化 PDF $xg(x)$。我们将我们的结果与之前的单系综晶格计算以及选定的全局拟合进行比较。
We present the first physical-continuum limit $x$-dependent nucleon gluon distribution from lattice QCD using the pseudo-PDF approach, on lattice ensembles with $2+1+1$ flavors of highly improved staggered quarks (HISQ), generated by MILC Collaboration. We use clover fermions for the valence action on three lattice spacings $a \approx 0.9$, 0.12 and 0.15~fm and three pion masses $M_\pi \approx 220$, 310 and 690~MeV, with nucleon two-point measurements numbering up to $O(10^6)$ and nucleon boost momenta up to 3~GeV. We study the lattice-spacing and pion-mass dependence of the reduced pseudo-ITD matrix elements obtained from the lattice calculation, then extrapolate them to the continuum-physical limit before extracting $xg(x)/\langle x \rangle_g$. We use the gluon momentum fraction $\langle x \rangle_g$ calculated from the same ensembles to determine the nucleon gluon unpolarized PDF $xg(x)$ for the first time entirely through lattice-QCD simulation. We compare our results with previous single-ensemble lattice calculations, as well as selected global fits.