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

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〉 and |qqqg〉, which are usually neglected in the WW approximation. This work provides new nonperturbative input for future experiments at the EicC and EIC on high-twist effects, especially interference effects among multiple partons.

Keywords

• Light-front quantization
• Nucleon
• Subleading twist TMDs and PDFs
• Quark-gluon correlations