LaMET 2023

Moments of proton GPDs from the OPE of nonlocal quark bilinears up to NNLO

26 Jul 2023, 15:00

30m

Speaker

Xiang Gao (Argonne National Lab)

Description

We present a lattice QCD determination of Mellin moments of unpolarized generalized parton distributions (GPDs) of the proton from an analysis of the quasi-GPD matrix elements within the short-distance factorization framework. We perform our calculation on an $N_f$=2+1+1 twisted mass fermions ensemble with a clover improvement at lattice spacing $a=0.093$ fm and a pion mass of $m_{\pi }=260$ MeV. Focusing on the zero-skewness case, the quasi-GPDs are calculated from the ${\gamma }_0$ definition, as well as a recently proposed Lorentz-invariant definition. We utilize data on both symmetric and asymmetric kinematic frames, which allows us to obtain the Mellin moments for several values of the momentum transfer, $-t$, in the range 0.17 to $2.77{\mathrm{G}\mathrm{e}\mathrm{V}}^2$. We use the ratio scheme for GPDs, i.e. renormalization group invariant ratios with leading-twist factorization formula and perturbatively calculated matching coefficients up to the next-next-to-leading order (NNLO) to extract Mellin moments of GPDs.

Presentation materials

GPD_XG.pdf