We present the first lattice results on isovector unpolarized and longitudinally polarized parton distribution functions (PDFs) at physical pion mass. The PDFs are obtained using the large-momentum effective field theory (LaMET) framework where the full Bjorken-x dependence of finite-momentum PDFs, called "quasi-PDFs", can be calculated on the lattice. The quasi-PDF nucleon matrix elements are renormalized nonperturbatively in RI/MOM-scheme. However, the recent renormalized quasi-PDFs suffer from unphysical oscillations that alter the shape of the true distribution as a function of Bjorken-x. In this paper, we propose two possible solutions to overcome this problem, and demonstrate the efficacy of the methods on the 2+1+1-flavor lattice data at physical pion mass with lattice spacing 0.09~fm and volume (5.76\mboxfm)3.
@article{arxiv.1708.05301,
title = {Improved Parton Distribution Functions at Physical Pion Mass},
author = {Huey-Wen Lin and Jiunn-Wei Chen and Tomomi Ishikawa and Jian-Hui Zhang},
journal= {arXiv preprint arXiv:1708.05301},
year = {2018}
}