Equation-of-motion and Lorentz-invariance relations for tensor-polarized parton distribution functions of spin-1 hadrons

TL;DR

This paper derives relations among tensor-polarized parton distribution functions of spin-1 hadrons using equations of motion, aiding the understanding and constraining of these functions for upcoming experimental measurements.

Contribution

It introduces equation-of-motion relations for tensor-polarized distribution functions of spin-1 hadrons, expanding theoretical tools for analyzing their internal structure.

Findings

Derived relations among collinear distribution functions

Constrained multiparton correlation functions

Enhanced theoretical framework for spin-1 hadron structure

Abstract

Structure functions of polarized spin-1 hadrons will be measured at various accelerator facilities in the near future. Recently, transverse-momentum-dependent and collinear parton distribution functions were theoretically proposed at twist 3 and twist 4 in addition to the twist-2 ones, so that full investigations became possible for structure functions of spin-1 hadrons in the same level with those of the spin-1/2 nucleons. Furthermore, twist-3 tensor-polarized multiparton distribution functions were also recently found for spin-1 hadrons. In this work, we show relations among the collinear parton- and multiparton-distribution functions for spin-1 hadrons by using equation of motion for quarks. These relations are valuable in constraining the distribution functions and learning about multiparton correlations in spin-1 hadrons.