Hadronic structure on the light-front V. Diquarks, Nucleons and multiquark Fock components

TL;DR

This paper investigates the role of diquark correlations and instanton-induced interactions in light-front quark models of hadronic structure, connecting spectroscopy with parton distributions through QCD evolution.

Contribution

It introduces a quasi-local four-fermion 't Hooft interaction to model diquarks and sea quark effects, bridging hadronic spectroscopy and parton observables.

Findings

Diquark correlations significantly influence hadronic structure.

Instanton effects generate sea quark asymmetries.

DGLAP evolution connects spectroscopy with parton distributions.

Abstract

This work is a continuation in our series of papers, that addresses quark models of hadronic structure on the light front, motivated by the QCD vacuum structure and lattice results. In this paper we focus on the importance of diquark correlations, which we describe by a quasi-local four-fermion effective 't Hooft interaction induced by instantons. The same interaction is also shown to generate extra quark-antiquark pair of the "sea". Its higher order iteration can be included via "pion-mediation": both taken together yield a quantitative description of the observed flavor asymmetry of antiquarks sea. Finally we discuss the final step needed to bridge the gap between hadronic spectroscopy and parton observables, by forward DGLAP evolution towards the chiral upper scale of $\sim 1\, {\rm GeV}^2$.