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arXiv · 2602.14260

Accessing the Gluon Momentum Fraction of Nucleons through the Gradient Flow

Robert Edwards·Joe Karpie·Lorenzo Maio·Christopher J. Monahan·Kostas Orginos·David Richards·Alexandru M. Sturzu·Savvas Zafeiropoulos
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Abstract

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 _g(\mu = 2 GeV) = 0.482(35), where we quote only statistical uncertainties.

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Robert Edwards, Joe Karpie, Lorenzo Maio, Christopher J. Monahan, Kostas Orginos, David Richards, Alexandru M. Sturzu, Savvas Zafeiropoulos. 2026-02-15. Accessing the Gluon Momentum Fraction of Nucleons through the Gradient Flow. https://arxiv.org/abs/2602.14260

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