Deep Inelastic Processes and the Equations of Motion

TL;DR

This paper explores how the Politzer theorem constrains quark correlators, reducing the number of independent distribution and fragmentation functions at high Q^2, and proposes new methods for measuring transversity and understanding azimuthal asymmetries.

Contribution

It introduces an approach based on the Politzer theorem that constrains nucleon structure functions and offers an alternative way to determine transversity distributions.

Findings

Constraints on distribution functions at large Q^2

Predictions for azimuthal asymmetries' Q^2-dependence

Implications for sum rules like Burkhardt-Cottingham

Abstract

We show that the Politzer theorem on the equations of motion implies approximate constraints on the quark correlator, restricting considerably, for sufficiently large Q^2, the number of independent distribution functions that characterize the internal structure of the nucleon, and of independent fragmentation functions. This result leads us to suggesting an alternative method for determining transversity. Moreover our approach implies predictions on the Q^2-dependence of some azimuthal asymmetries, like Sivers, Qiu-Sterman and Collins asymmetry. Lastly, we discuss some implications on the Burkhardt-Cottingham and Efremov-Leader-Teryaev sum rules.