Proton's isovector PDF with updated analysis of large-momentum lattice data
Abstract
The proton's unpolarized $u(x)-d(x)$ parton distribution function (PDF) has been studied by a number of lattice QCD groups through large momentum expansion. However, due to lattice artifacts (excited state contaminations, unphysical pion masses, and discretization effects) and less-advanced theoretical analysis (renormalizations, large-distance extrapolations, and large-log resummations), the resulting PDFs cannot be compared strictly with experimental data. By using the state-of-the-art theoretical tools and mitigating the lattice artifacts empirically, we reanalyze the available datasets in the literature and find that the new PDF for the physical-limit-extrapolated dataset (MSULat20) is consistent with global fits within ∼1σ, while others are broadly compatible. This provides evidence that large momentum expansion is capable of accurately predicting the x-dependence of the PDFs when ideal lattice data become available.
Versions
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BibTeX
@misc{ji2026protons,
title = {{Proton's isovector PDF with updated analysis of large-momentum lattice data}},
author = {Xiangdong Ji and Yushan Su},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.22224},
eprint = {2606.22224},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.22224},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Proton's isovector PDF with updated analysis of large-momentum lattice data
AU - Xiangdong Ji
AU - Yushan Su
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2606.22224
UR - https://arxiv.org/abs/2606.22224
AB - The proton's unpolarized $u(x)-d(x)$ parton distribution function (PDF) has been studied by a number of lattice QCD groups through large momentum expansion. However, due to lattice artifacts (excited state contaminations, unphysical pion masses, and discretization effects) and less-advanced theoretical analysis (renormalizations, large-distance extrapolations, and large-log resummations), the resulting PDFs cannot be compared strictly with experimental data. By using the state-of-the-art theoretical tools and mitigating the lattice artifacts empirically, we reanalyze the available datasets in the literature and find that the new PDF for the physical-limit-extrapolated dataset (MSULat20) is consistent with global fits within ∼1σ, while others are broadly compatible. This provides evidence that large momentum expansion is capable of accurately predicting the x-dependence of the PDFs when ideal lattice data become available.
ER -