Pion generalized parton distribution from lattice QCD
Jiunn-Wei Chen, Huey-Wen Lin, Jian-Hui Zhang
Abstract
We present the first lattice calculation of the valence-quark generalized parton distribution (GPD) of the pion using the large-momentum effective theory (LaMET) approach. We focus on the zero-skewness limit, where the GPD has a probability-density interpretation in the longitudinal Bjorken xand the transverse impact-parameter distributions. Our calculation is done using clover valence fermions on an ensemble of gauge configurations with 2 +1 +1flavors (degenerate up/down, strange and charm) of highly im-proved staggered quarks (HISQ) with lattice spacing a≈0.12fm, box size L ≈3fm and pion mass mπ≈310MeV. The parton distribution function and the form factor are reproduced as special limits of the GPD as expected. Due to the large errors, this exploratory study does not show a clear preference among different model assumptions about the kinematic dependence of the GPD. To discriminate betweenthese assumptions, future studies using higher-statistics data will be crucial.