Instanton effects in twist-3 generalized parton distributions

Oct 25, 2023
6 pages
Published in:
  • Phys.Lett.B 848 (2024) 138387
  • Published: Dec 7, 2023
e-Print:
Report number:
  • JLAB-THY-23-3946

Citations per year

2023202420251
Abstract: (Elsevier B.V.)
The instanton vacuum picture is used to study hadronic matrix elements of the twist-3 (dimension-4, spin-1) QCD operators measuring the quark spin density and spin-orbit correlations. The QCD operators are converted to effective operators in the low-energy effective theory emerging after chiral symmetry breaking, in a systematic approach based on the diluteness of the instanton medium and the 1/Nc expansion. The instanton fields induce spin-flavor-dependent “potential” terms in the effective operators, complementing the “kinetic” terms from the quark field momenta. As a result, the effective operators obey the same equation-of-motion relations as the original QCD operators. The spin-orbit correlations are qualitatively different from naive quark model expectations.
Note:
  • 6 pages, 1 figure
  • instanton: effect
  • twist: 3
  • quantum chromodynamics: operator
  • expansion 1/N: color
  • symmetry breaking: chiral
  • quark: spin: density
  • generalized parton distribution
  • effective operator
  • correlation
  • quark model