First Lattice QCD Study of Proton Twist-3 GPDs

Abstract

We present first results on selected twist-3 quark GPDs using the quasi-distribution method. This approach relates lattice QCD data and light-cone distribution functions using Large Momentum Effective Theory (LaMET). We calculate quark-antiquark correlators of boosted nucleons coupled to non-local operators with vector and axial Dirac structure, which is transverse to the momentum boost. We use three values of the momentum boost, namely 0.83, 1.25, 1.67 GeV. The GPDs are defined in the symmetric (Breit) frame, which we implement here with 4-vector momentum transfer squared of 0, 0.69 and 1.39 GeV 2 , all at zero skewness. The calculation is performed using one ensemble of two degenerate light, a strange and a charm quark (𝑁 𝑓 = 2 + 1 + 1) of maximally twisted mass fermions with a clover term, corresponding to a pion mass of 260 MeV.

One-Loop Hybrid Renormalization Matching Kernels for Quasi-Parton Distributions

“…with continuum extrapolations at physical pion mass ) [86] have shown reasonable agreement with phenomenological results extracted from the experimental data. Encouraged by this success, LaMET has also been extended to twist-three PDFs [87][88][89] and generalized parton distributions (GPDs) [90], as well as gluon [91][92][93], strange and charm distributions [94]. It was also applied to meson distribution amplitudes (DAs) [21,[95][96][97][98] and GPDs [99][100][101][102][103][104].…”