Continuum-extrapolated NNLO valence PDF of the pion at the physical point
Continuum-extrapolated NNLO valence PDF of the pion at the physical point
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DOI：
10.1103/physrevd.106.114510
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发表时间：
2022-08
影响因子：
5
通讯作者：
Xiang Gao;Andrew D. Hanlon;Nikhil Karthik;S. Mukherjee;P. Petreczky;P. Scior;S. Shi;S. Syritsyn;Yong Zhao;K. Zhou
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文献类型：
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作者：
Xiang Gao;Andrew D. Hanlon;Nikhil Karthik;S. Mukherjee;P. Petreczky;P. Scior;S. Shi;S. Syritsyn;Yong Zhao;K. Zhou
本文采用次-次主导阶（NNLO）微扰QCD匹配方法计算了π介子的价部分子分布函数。我们的计算是基于3个规范系综的2+1 Escheravor高度改进的交错夸克和Wilson-Clover价夸克，对应于介子质量m π = 140 MeV，晶格间距a = 0。076 fm和m π = 300 MeV，a = 0。04，0。06 fm.这使我们能够第一次给出π介子在物理点上的非线性零价概率密度函数的连续外推晶格QCD结果。对双定域π矩阵元的重整化群不变量（RGI）比进行超前扭转展开，得到了PDF的二阶、四阶和六阶Mellin矩。我们使用深度神经网络（DNN）从实空间RGI比率以及使用混合方案重正化的动量空间矩阵元素重建NNLO PDF的Bjorken- x依赖性。我们所有的结果与xFitter和JAM合作进行的实验数据的全局拟合结果基本一致。
We present lattice QCD calculations of valence parton distribution function (PDF) of pion em-ploying next-to-next-leading-order (NNLO) perturbative QCD matching. Our calculations are based on three gauge ensembles of 2+1 flavor highly improved staggered quarks and Wilson–Clover valance quarks, corresponding to pion mass m π = 140 MeV at a lattice spacing a = 0 . 076 fm and m π = 300 MeV at a = 0 . 04 , 0 . 06 fm. This enables us to present, for the first time, continuum-extrapolated lattice QCD results for NNLO valence PDF of the pion at the physical point. Applying leading-twist expansion for renormalization group invariant (RGI) ratios of bi-local pion matrix elements with NNLO Wilson coefficients we extract 2 nd , 4 th and 6 th Mellin moments of the PDF. We reconstruct the Bjorken- x dependence of the NNLO PDF from real-space RGI ratios using a deep neural network (DNN) as well as from momentum-space matrix elements renormalized using a hybrid-scheme. All our results are in broad agreement with the results of global fits to the experimental data carried out by the xFitter and JAM collaborations.