We calculate the gluon momentum fraction of the nucleon using lattice quantum chromodynamics (QCD), with a nonperturbative renormalization technique based on the gradient flow. The gluon momentum fraction is determined on a single Wilson-clover ensemble using Nf = 2+1 flavors with pion mass 358 MeV and lattice spacing 0.094 fm. We employ the variational method to reduce excited-state contamination and apply the distillation framework to ensure a large operator basis. To reduce systematic uncertainties, we apply Bayesian model averaging to all fit procedures. We apply matching coefficients to the flow-time dependent lattice results to recover the gluon momentum fraction in the MS-scheme at 2 GeV. Our final result is <x>_g(\mu = 2 GeV) = 0.482(35), where we quote only statistical uncertainties.
@article{arxiv.2602.14260,
title = {Accessing the Gluon Momentum Fraction of Nucleons through the Gradient Flow},
author = {Robert Edwards and Joe Karpie and Lorenzo Maio and Christopher J. Monahan and Kostas Orginos and David Richards and Alexandru M. Sturzu and Savvas Zafeiropoulos},
journal= {arXiv preprint arXiv:2602.14260},
year = {2026}
}