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. An analysis of the short-distance behavior of the space-like matrix elements using matching coefficients computed to next-to-leading order (NLO) exposes the desired PDF up to this additional z 2 contamination. 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 μ 2. The leading-twist helicity PDFs as well as several sources of systematic error, including higher-twist effects, discretization errors, and the aforementioned z 2 contaminating amplitude are jointly determined by characterizing the computed pseudo-distribution in a basis of Jacobi polynomials. The Akaike Information Criterion is exploited to effectively average over distinct model parameterizations and cuts on the 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.
{ "_oai": { "updated": "2023-06-24T00:33:42Z", "id": "oai:repo.scoap3.org:76482", "sets": [ "JHEP" ] }, "authors": [ { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" } ], "surname": "Edwards", "email": "edwards@jlab.org", "full_name": "Edwards, Robert", "given_names": "Robert" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" } ], "surname": "Egerer", "email": "cegerer@jlab.org", "full_name": "Egerer, Colin", "given_names": "Colin" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" } ], "surname": "Karpie", "email": "jkarpie@jlab.org", "full_name": "Karpie, Joseph", "given_names": "Joseph" }, { "affiliations": [ { "country": "USA", "value": "Department of Physics, William and Mary, 300 Ukrop Way, Williamsburg, VA, 23187, USA", "organization": "William and Mary" } ], "surname": "Karthik", "email": "nkarthik.work@gmail.com", "full_name": "Karthik, Nikhil", "given_names": "Nikhil" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" }, { "country": "USA", "value": "Department of Physics, William and Mary, 300 Ukrop Way, Williamsburg, VA, 23187, USA", "organization": "William and Mary" } ], "surname": "Monahan", "email": "cjmonahan@wm.edu", "full_name": "Monahan, Christopher", "given_names": "Christopher" }, { "affiliations": [ { "country": "USA", "value": "Department of Physics, Old Dominion University, 4600 Elkhorn Ave., Norfolk, VA, 23529, USA", "organization": "Old Dominion University" } ], "surname": "Morris", "email": "morris3wh@gmail.com", "full_name": "Morris, Wayne", "given_names": "Wayne" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" }, { "country": "USA", "value": "Department of Physics, William and Mary, 300 Ukrop Way, Williamsburg, VA, 23187, USA", "organization": "William and Mary" } ], "surname": "Orginos", "email": "knorgi@wm.edu", "full_name": "Orginos, Kostas", "given_names": "Kostas" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" }, { "country": "USA", "value": "Department of Physics, Old Dominion University, 4600 Elkhorn Ave., Norfolk, VA, 23529, USA", "organization": "Old Dominion University" } ], "surname": "Radyushkin", "email": "radyush@jlab.org", "full_name": "Radyushkin, Anatoly", "given_names": "Anatoly" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" } ], "surname": "Richards", "email": "dgr@jlab.org", "full_name": "Richards, David", "given_names": "David" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" } ], "surname": "Romero", "email": "eromero@jlab.org", "full_name": "Romero, Eloy", "given_names": "Eloy" }, { "affiliations": [ { "country": "USA", "value": "Thomas Jefferson National Accelerator Facility, 12000 Jefferson Ave., Newport News, VA, 23606, USA", "organization": "Thomas Jefferson National Accelerator Facility" }, { "country": "USA", "value": "Department of Physics, William and Mary, 300 Ukrop Way, Williamsburg, VA, 23187, USA", "organization": "William and Mary" } ], "surname": "Sufian", "email": "sufian@jlab.org", "full_name": "Sufian, Raza", "given_names": "Raza" }, { "affiliations": [ { "country": "France", "value": "Aix Marseille Univ, Universit\u00e9 de Toulon, CNRS, CPT, Marseille, France", "organization": "Aix Marseille Univ, Universit\u00e9 de Toulon, CNRS, CPT" } ], "surname": "Zafeiropoulos", "email": "savvas.zafeiropoulos@cpt.univ-mrs.fr", "full_name": "Zafeiropoulos, Savvas", "given_names": "Savvas" } ], "titles": [ { "source": "Springer", "title": "Non-singlet quark helicity PDFs of the nucleon from pseudo-distributions" } ], "dois": [ { "value": "10.1007/JHEP03(2023)086" } ], "publication_info": [ { "page_end": "51", "journal_title": "Journal of High Energy Physics", "material": "article", "journal_volume": 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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. An analysis of the short-distance behavior of the space-like matrix elements using matching coefficients computed to next-to-leading order (NLO) exposes the desired PDF up to this additional z 2 contamination. 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 \u03bc 2. The leading-twist helicity PDFs as well as several sources of systematic error, including higher-twist effects, discretization errors, and the aforementioned z 2 contaminating amplitude are jointly determined by characterizing the computed pseudo-distribution in a basis of Jacobi polynomials. The Akaike Information Criterion is exploited to effectively average over distinct model parameterizations and cuts on the 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." } ], "imprints": [ { "date": "2023-03-14", "publisher": "Springer" } ] }