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FZJ-2025-00784

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Quark orbital angular momentum in the proton from a twist-3 generalized parton distribution

Engelhardt, M. (Corresponding author) ; Hasan, N. ; Krieg, S.FZJ* ; Liuti, S. ; Meinel, S. ; Negele, J. ; Pochinsky, A. ; Rodekamp, M.FZJ* ; Syritsyn, S.

2024
Sissa Medialab Trieste Trieste, Italy

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Please use a persistent id in citations: doi:10.22323/1.456.0075  doi:10.34734/FZJ-2025-00784

Abstract: Quark orbital angular momentum in the proton is evaluated via a Lattice QCD calculation of thesecond Mellin moment of the twist-3 generalized parton distribution ˜E2T in the forward limit. Theconnection between this approach to quark orbital angular momentum and approaches previouslyutilized in Lattice QCD calculations, via generalized transverse momentum-dependent partondistributions and via Ji’s sum rule, is reviewed. This connection can be given in terms of Lorentzinvariance and equation of motion relations. The calculation of the second Mellin moment of˜E2T proceeds via a finite-momentum proton matrix element of a quark bilocal operator with astraight-line gauge connection and separation in both the longitudinal and transverse directions.The dependence on the former component serves to extract the second Mellin moment, whereasthe dependence on the latter component provides a transverse momentum cutoff for the matrixelement. Furthermore, a derivative of the matrix element with respect to momentum transfer inthe forward limit is required, which is obtained using a direct derivative method. The calculationutilizes a clover fermion ensemble at pion mass 317 MeV. The resulting quark orbital angularmomentum is consistent with previous evaluations through alternative approaches, albeit withgreater statistical uncertainty using a comparable number of samples

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Contributing Institute(s):

1. Jülich Supercomputing Center (JSC)

Research Program(s):

1. 5111 - Domain-Specific Simulation & Data Life Cycle Labs (SDLs) and Research Groups (POF4-511) (POF4-511)
2. SDS005 - Towards an integrated data science of complex natural systems (PF-JARA-SDS005) (PF-JARA-SDS005)
3. NRW-FAIR (NW21-024-A) (NW21-024-A)

Appears in the scientific report 2024

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