Moments of axial-vector GPD from lattice QCD: quark helicity, orbital angular momentum, and spin-orbit correlation

• DOI: 10.1007/jhep01(2025)146
• Publication Date: 2025-02-03T18:49:01Z
• Authors: Shohini Bhattacharya; Krzysztof Cichy; Martha Constantinou; Xiang Gao; Andreas Metz; Joshua Miller; Swagato Mukherjee; Peter Petreczky; Fernanda Steffens; Yong Zhao
• Keywords: Nuclear Theory; Parton Distributions; High Energy Physics - Lattice (hep-lat); Hadronic Spectroscopy; FOS: Physical sciences; Lattice QCD; Structure and Interactions; QC770-798; High Energy Physics - Experiment; Nuclear Theory (nucl-th); High Energy Physics - Phenomenology; High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice; High Energy Physics - Phenomenology (hep-ph); Nuclear and particle physics. Atomic energy. Radioactivity

A bstract In this work, we present a lattice QCD calculation of the Mellin moments twist-2 axial-vector generalized parton distribution (GPD), $$ \overset{\sim }{H}\left(x,\xi, t\right) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>H</mml:mi> <mml:mo>~</mml:mo> </mml:mover> <mml:mfenced> <mml:mi>x</mml:mi> <mml:mi>ξ</mml:mi> <mml:mi>t</mml:mi> </mml:mfenced> </mml:math> , at zero skewness, ξ with multiple values momentum transfer, t . Our analysis employs short-distance factorization framework on ratio-scheme renormalized quasi-GPD matrix elements. The calculations are based an N f = 2 + 1 twisted mass fermions ensemble clover improvement, spacing 0 093 fm, and pion m π 260 MeV. We consider both iso-vector iso-scalar cases, utilizing next-to-leading-order perturbative matching while omitting disconnected contributions gluon mixing in case. For first time, determine }{H} up to fifth order. From these moments, discuss quark helicity orbital angular nucleon spin, as well spin-orbit correlations quarks. Additionally, perform Fourier transform over which allows us explore spin structure impact-parameter space.