Abstract
We present the first Monte Carlo based global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs) that includes nucleon isovector matrix elements in coordinate space from lattice QCD. We investigate the degree of universality of the extracted PDFs when the lattice and experimental data are treated under the same conditions within the Bayesian likelihood analysis. For the unpolarized sector, we find rather weak constraints from the current lattice data on the phenomenological PDFs, and difficulties in describing the lattice matrix elements at large spatial distances. In contrast, for the polarized PDFs we find good agreement between experiment and lattice data, with the latter providing significant constraints on the spin-dependent isovector quark and antiquark distributions.
Highlights
Recent years have witnessed remarkable advances in the extraction of light-cone parton distributions from firstprinciples lattice QCD calculations of nucleon matrix elements of nonlocal operators
Our Bayesian inference for the parton distribution functions (PDFs) is based on the Monte Carlo (MC) methods developed by the Jefferson Lab Angular Momentum (JAM) Collaboration [9,10,11], which involve parametrizing the PDFs at an input scale μ0 and solving the DGLAP evolution equations to evaluate the various observable considered in the analysis at different scales
In this paper we have performed the first combined MCbased global QCD analysis of spin-averaged and spindependent PDFs, using both experimental data and matrix elements computed from first principles in lattice QCD
Summary
We present the first Monte Carlo based global QCD analysis of spin-averaged and spin-dependent parton distribution functions (PDFs) that includes nucleon isovector matrix elements in coordinate space from lattice QCD. We investigate the degree of universality of the extracted PDFs when the lattice and experimental data are treated under the same conditions within the Bayesian likelihood analysis. We find rather weak constraints from the current lattice data on the phenomenological PDFs, and difficulties in describing the lattice matrix elements at large spatial distances. For the polarized PDFs we find good agreement between experiment and lattice data, with the latter providing significant constraints on the spin-dependent isovector quark and antiquark distributions
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