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Title Non-singlet quark helicity PDFs of the nucleon from pseudo-distributions
Authors Robert Edwards, Colin Egerer, Joseph Karpie, FNU Nikhil Sridharan Karthik, Christopher Monahan, Wayne Morris, Kostas Orginos, Anatoly Radyushkin, David Richards, Eloy Romero Alcalde, Raza Sufian, Savvas Zafeiropoulos
JLAB number JLAB-THY-22-3751
LANL number arXiv:2211.04434
Other number DOE/OR/23177-5644
Document Type(s) (Journal Article) 
Associated with EIC: No
Supported by Jefferson Lab LDRD Funding: No
Funding Source: Nuclear Physics (NP)

Compiled for Journal of High Energy Physics
Page(s) 86
Publication Abstract: The non-singlet helicity quark parton distribution functions (PDFs) of the nucleon are determined from lattice QCD, by jointly leveraging pseudo-distributions and the distillation spatial smearing paradigm. A Lorentz decomposition of appropriately isolated space-like matrix elements reveals pseudo-distributions that contain information on the leading-twist helicity PDFs, as well as an invariant amplitude that induces an additional $z^2$ contamination of the leading-twist signal. Novel to this calculation is the establishment of a prescription for rigorously removing this contamination from the leading-twist signal. An analysis of the short-distance behavior of the leading pseudo-distribution using matching coefficients computed to next-to-leading order (NLO) exposes the desired PDF. Due to the non-conservation of the axial current, we elect to isolate the helicity PDFs normalized by the nucleon axial charge at the same scale $\mu^2$. In particular, the leading-twist helicity PDFs as well as several sources of systematic error, such as higher-twist effects and discretization errors, are jointly determined by characterizing the computed pseudo-distributions in a basis of Jacobi polynomials. The Akaike Information Criterion is exploited to effectively average over distinct model parameterizations and cuts on the leading pseudo-distribution. Encouraging agreement is observed with recent global analyses of each non-singlet quark helicity PDF, notably a rather small non-singlet anti-quark helicity PDF for all quark momentum fractions.
Experiment Numbers: other
Document: pdf
Accepted Manuscript: JHEP03(2023)086.pdf
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