We perform a new global analysis of spin-dependent parton distribution functions with the inclusion of Ioffe time pseudo-distributions computed in lattice QCD (LQCD), which are directly sensitive to the gluon helicity distribution, Δg. These lattice data have an analogous relationship to parton distributions as do experimental cross sections, and can be readily included in global analyses. We focus in particular on the constraining capability of current LQCD data on the sign of Δg at intermediate parton momentum fractions x, which was recently brought into question by analysis of data in the absence of parton positivity constraints. We find that present LQCD data cannot discriminate between positive and negative Δg solutions, although significant changes in the solutions for both the gluon and quark sectors are observed.
@article{arxiv.2310.18179,
title = {Gluon helicity from global analysis of experimental data and lattice QCD Ioffe time distributions},
author = {J. Karpie and R. M. Whitehill and W. Melnitchouk and C. Monahan and K. Orginos and J. -W. Qiu and D. G. Richards and N. Sato and S. Zafeiropoulos},
journal= {arXiv preprint arXiv:2310.18179},
year = {2023}
}