Generalized parton distributions from the pseudo-distribution approach on the lattice
arxiv(2024)
摘要
Generalized parton distributions (GPDs) are key quantities for the
description of a hadron's three-dimensional structure. They are the current
focus of all areas of hadronic physics – phenomenological, experimental, and
theoretical, including lattice QCD. Synergies between these areas are desirable
and essential to achieve precise quantification and understanding of the
structure of, particularly nucleons, as the basic ingredients of matter. In
this paper, we investigate, for the first time, the numerical implementation of
the pseudo-distribution approach for the extraction of zero-skewness GPDs for
unpolarized quarks. Pseudo-distributions are Euclidean parton correlators
computable in lattice QCD that can be perturbatively matched to the light-cone
parton distributions of interest. Being closely related to the
quasi-distributions and coming from the same lattice-extracted matrix elements,
they are, however, subject to different systematic effects. We use the data
previously utilized for quasi-GPDs and extend it with other momentum transfers
and nucleon boosts, in particular a higher one (P_3=1.67 GeV) with eight-fold
larger statistics than the largest one used for quasi-distributions (P_3=1.25
GeV). We renormalize the matrix elements with a ratio scheme and match the
resulting Ioffe time distributions to the light cone in coordinate space. The
matched distributions are then used to reconstruct the x-dependence with a
fitting ansatz.We investigate some systematic effects related to this
procedure, and we also compare the results with the ones obtained in the
framework of quasi-GPDs. Our final results involve the invariant four-momentum
transfer squared (-t) dependence of the flavor non-singlet (u-d) H and
E GPDs.
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