Reconstructing parton densities at large fractional momenta

Abstract

Parton distribution functions (PDFs) are nonperturbative objects defined by nonlocal light-cone correlations. They cannot be computed directly from Quantum Chromodynamics (QCD). Using a standard lattice QCD approach, it is possible to compute moments of PDFs, which are matrix elements of local operators. Recently, an alternative approach has been proposed, based on the introduction of quasi-parton distribution functions (quasi-PDFs), which are matrix elements of equal-time spatial correlations and hence calculable on lattice. Quasi-PDFs approach standard PDFs in the limit of very large longitudinal proton momenta $P^z$. This limit is not attainable in lattice simulations, and quasi-PDFs fail to reproduce PDFs at high fractional longitudinal momenta. In this paper, we propose a method to improve the reconstruction of PDFs by combining information from quasi-PDFs and from the Mellin moments of regular PDFs. We test our method using the diquark spectator model for up and down valence distributions of both unpolarized and helicity PDFs. In the future, the method can be used to produce PDFs entirely based on lattice QCD results.

arXiv comment12 pages, 7 double-panel figures in pdf, RevTeX4-1

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• Nonperturbative Evolution of Parton Quasi-Distributions
• Systematic uncertainties in parton distribution functions from lattice QCD simulations at the physical point
• Gluon quasidistribution function at one loop
• Pion and kaon valence-quark quasiparton distributions
• Flavor non-singlet parton distribution functions from lattice QCD at physical quark masses via the pseudo-distribution approach
• Generalized quasi parton distributions in a diquark spectator model
• On the power divergence in quasi gluon distribution function
• The role of zero-mode contributions in the matching for the twist-3 PDFs $e(x)$ and $h_L(x)$
• Pion Distribution Amplitude and Quasi-Distributions
• One-loop matching for the twist-3 parton distribution $g_T(x)$
• Renormalization of Wilson-line operators in the presence of nonzero quark masses
• Exploring twist-2 GPDs through quasi-distributions in a diquark spectator model
• Quasi parton distribution function and quasi generalized parton distribution of the pion meson in a spectator model
• T-odd generalized and quasi transverse momentum dependent parton distribution in a scalar spectator model
• The quark quasi Sivers function and quasi Boer-Mulders function in a spectator diquark model