String-based axial and helicity-flip GPDs: A comparison to lattice QCD

Hechenberger, Florian [Stony Brook University, NY (United States)] (ORCID:000900062851585X); Mamo, Kiminad A. [College of William and Mary, Williamsburg, VA (United States)] (ORCID:0000000331234398); Zahed, Ismail [Stony Brook University, NY (United States)]

doi:10.1103/7lxw-g6tq

DOE OSTI · 3021120

String-based axial and helicity-flip GPDs: A comparison to lattice QCD

Hechenberger, Florian [Stony Brook University, NY (United States)] (ORCID:000900062851585X)·Mamo, Kiminad A. [College of William and Mary, Williamsburg, VA (United States)] (ORCID:0000000331234398)·Zahed, Ismail [Stony Brook University, NY (United States)]

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Abstract

We construct an analytic, string-based representation of the nucleon’s axial and helicity-flip conformal moments of generalized parton distributions (GPDs) that holds for skewness and for both the quark and gluon channels. The starting point is the Mellin-Barnes resummation of the conformal partial-wave expansion, where the moments are parametrized by open- (Reggeon) and closed-string (Pomeron) trajectories with slopes determined by experimental form factors and meson/glueball spectroscopy. The forward limits are fixed by the empirical unpolarized and polarized parton distributions. Polynomiality, crossing symmetry, and support are satisfied by construction. After next-to-leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi/Efremov-Radyushkin-Brodsky-Lepage evolution to μ = 2 GeV our analytic framework (i) reproduces some of the currently available lattice moments of E and H˜ in the nonsinglet sector, (ii) predicts sea-quark and gluon polarized moments that will be testable by forthcoming simulations and experiments at Jefferson Lab and the future Electron-Ion Collider, and (iii) yields axial and helicity-flip GPDs in x-space in reasonable agreement with lattice QCD.

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Hechenberger, Florian [Stony Brook University, NY (United States)] (ORCID:000900062851585X), Mamo, Kiminad A. [College of William and Mary, Williamsburg, VA (United States)] (ORCID:0000000331234398), Zahed, Ismail [Stony Brook University, NY (United States)]. 2025-10-16. String-based axial and helicity-flip GPDs: A comparison to lattice QCD. https://doi.org/10.1103/7lxw-g6tq

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