Polarized Parton Distributions in Light-Front Dynamics

TL;DR

This paper calculates polarized parton distributions in nucleons using a light-front constituent quark model, analyzing relativistic effects, covariance constraints, and the impact of gluonic structure, with implications for experimental measurements of transversity.

Contribution

It provides a covariant calculation of polarized structure functions within a light-front model, highlighting relativistic effects and the importance of covariance constraints in spin physics.

Findings

Relativistic effects significantly influence polarized distributions.

Covariance constraints are essential for accurate spin structure modeling.

Measurements of transversity can reveal covariance effects in nucleon structure.

Abstract

We present a consistent calculation of the structure functions within a light-front constituent quark model of the nucleon. Relativistic effects and the relevance of the covariance constraints are analyzed for polarized parton distributions. Various models, which differ in their gluonic structure at the hadronic scale, are investigated. The results of the full covariant calculation are compared with those of a non-relativistic approximation to show the structure and magnitude of the differences. It is also shown how measurements of transversity in doubly polarized Drell-Yan lepton pair production are a clearcut sign of covariance requirements for the spin.