论文标题
用晶格QCD探测核子奇异和魅力分布
Probing nucleon strange and charm distributions with lattice QCD
论文作者
论文摘要
我们介绍了使用大型摩肌有效理论（LAMET）的第一个晶格QCD计算，对未极化的奇异和魅力部分分布函数进行了计算。我们使用MILC协作产生的高度改进的交错夸克（HISQ）的2+1+1个口味的晶格合奏，晶格间距$ a \ a \ a \ 0.12 $ fm和$m_π\ $m_π\ 310 $ MEV，以及三叶草价费用，以及带有两个价值pion pion pion质量：310和690 mev。我们使用动量吸收源将信号提高到核子增强动量$ p_z = 2.18 $ GEV，并确定RI/MOM方案中的非扰动重新归一化因子。我们将晶格结果与从CT18NNLO和NNPDF3.1NNLO Global Fits匹配的PDF获得的矩阵元素进行了比较。我们的数据支持全球PDF拟合中通常使用的奇怪抗散动和魅力对称性的假设，并且我们发现在中$ x $中的Parton分布小于预期的Parton分布。
We present the first lattice-QCD calculation of the unpolarized strange and charm parton distribution functions using large-momentum effective theory (LaMET). We use a lattice ensemble with 2+1+1 flavors of highly improved staggered quarks (HISQ) generated by MILC collaboration, with lattice spacing $a\approx 0.12$ fm and $M_π\approx 310$ MeV, and clover valence fermions with two valence pion masses: 310 and 690 MeV. We use momentum-smeared sources to improve the signal up to nucleon boost momentum $P_z=2.18$ GeV, and determine nonperturbative renormalization factors in RI/MOM scheme. We compare our lattice results with the matrix elements obtained from matching the PDFs from CT18NNLO and NNPDF3.1NNLO global fits. Our data support the assumptions of strange-antistrange and charm-anticharm symmetry that are commonly used in global PDF fits, and we find smaller than expected parton distribution at mid to small $x$.
