论文标题
2+1+1型晶格QCD的核子gluon分布函数
Nucleon Gluon Distribution Function from 2+1+1-Flavor Lattice QCD
论文作者
论文摘要
Parton分布函数（PDF）提供了有关Hadron中夸克和胶子的过程无关的信息。尽管可以从全球拟合到实验数据中获得Gluon PDF，但在大$ x $区域中并没有很好地限制它。理论上的Gluon-PDF研究要比夸克PDF的研究少得多。在这项工作中，我们介绍了第一个晶格QCD结果，该结果访问了核子的gluon未偏振PDF的$ x $依赖性。晶格计算是用核子动量的2.16 GEV进行的，晶格间距$ a \ a \大约0.12 $ fm，价质量为310和690 meV。我们使用减少的IOFFE时间分布来取消重新归一化，并实现与LightCone分布匹配的单层扰动pseudo-PDF。我们的矩阵元件在坐标空间中的结果与从CT18 NNLO和NNPDF3.1 NNLO的全局PDF拟合获得的矩阵元素一致。我们拟合的Gluon PDF被外推到物理斜质量质量可在$ x> 0.3 $区域中保持一致的结果。
The parton distribution functions (PDFs) provide process-independent information about the quarks and gluons inside hadrons. Although the gluon PDF can be obtained from a global fit to experimental data, it is not constrained well in the large-$x$ region. Theoretical gluon-PDF studies are much fewer than those of the quark PDFs. In this work, we present the first lattice-QCD results that access the $x$-dependence of the gluon unpolarized PDF of the nucleon. The lattice calculation is carried out with nucleon momenta up to 2.16 GeV, lattice spacing $a\approx0.12$ fm, with valence pion masses of 310 and 690 MeV. We use reduced Ioffe-time distributions to cancel the renormalization and implement a one-loop perturbative pseudo-PDF matching to the lightcone distribution. Our matrix element results in coordinate space are consistent with those obtained from the global PDF fits of CT18 NNLO and NNPDF3.1 NNLO. Our fitted gluon PDF extrapolated to the physical pion mass gives consistent results in the $x > 0.3$ region.
