Power corrections to TMD factorization for Z-boson production

TL;DR

This paper calculates the first power corrections to the TMD factorization formula for Z-boson production and Drell-Yan processes, clarifying when higher-twist effects become significant in high-energy hadron collisions.

Contribution

It provides the first explicit calculation of power corrections to TMD factorization for Z-boson production, expressed in terms of leading-twist TMDs using QCD equations of motion.

Findings

Power corrections are expressed via leading-twist TMDs.

Corrections become relevant at specific transverse momenta.

Results are at leading order in N_c.

Abstract

A typical factorization formula for production of a particle with a small transverse momentum in hadron-hadron collisions is given by a convolution of two leading-twist TMD parton densities with cross section of production of the final particle by the two partons. For practical applications at a given transverse momentum, though, one should estimate at what momenta the power corrections to TMD factorization formula due to higher-twist operators become essential. In this paper we calculate the first power corrections to TMD factorization formula for Z-boson production and Drell-Yan process in high-energy hadron-hadron collisions. At the leading order in $N_c$ power corrections are expressed in terms of leading-twist TMDs by QCD equations of motion.