Transverse structure of the proton beyond leading twist: A light-front Hamiltonian approach

TL;DR

This paper uses a light-front Hamiltonian approach within the Basis Light-Front Quantization framework to analyze the subleading twist transverse-momentum-dependent parton distribution functions of the proton, going beyond the common Wandzura-Wilczek approximation.

Contribution

It provides a systematic investigation of twist-3 TMDs, including genuine twist-3 terms involving quark-gluon correlations and interferences between Fock sectors, which are often neglected.

Findings

Decomposition of twist-3 TMDs into twist-2 and genuine twist-3 components.

Identification of quark-quark-gluon correlations in the proton.

Analysis of interferences between different light-front Fock sectors.

Abstract

Within the Basis Light-Front Quantization framework, we systematically investigate the subleading twist (twist-3) transverse-momentum-dependent parton distribution functions (TMDs) of the proton beyond the Wandzura-Wilczek (WW) approximation. The subleading twist TMDs are not independent and can be decomposed into twist-2 and genuine twist-3 terms from the equations of motion. The latter involves quark-quark-gluon correlations and contains interferences between two light-front Fock sectors, $|qqq\rangle$ and $|qqqg\rangle$, which are usually neglected in the WW approximation.