Unpolarized Isovector Nucleon PDF from LaMET

Large Momentum Effective Theory (LaMET) can be used to extract parton physics from lattice QCD calculation. It has a wide range of applications since its proposal, including PDF, TMD, DA, and GPD. Unpolarized isovector nucleon PDF has been widely studied in high precision through global fit with experimental data. So it is a natural benchmark to test LaMET and lattice calculation on the ability to control the systematic errors. Under LaMET framework, we present the lattice calculation of unpolarized isovector nucleon PDF on CLS ensembles H102 (a=0.0854fm), N203 (a=0.0644fm), and N302 (a=0.0500fm). The nucleon momentum is from 2.3 to 3.2 GeV. We adopt the Hybrid renormalization scheme with self-renormalization, which can eliminate the UV divergence without introducing extra non-perturbative effects. We adopt two-loop matching, which leads to a similar result with one-loop matching. As the momentum becomes larger, PDF from lattice calculation becomes consistent with PDF from global fit. Moreover, we find that there is more d_bar than u_bar up to x~0.3 in our calculation, which is consistent with experimental results of antimatter asymmetry.