Unitarity cutting rules for hard processes on nuclei

TL;DR

This paper discusses how the introduction of the saturation scale in heavy nuclei leads to a breakdown of linear k_p-factorization, replaced by nonlinear k_p-factorization, affecting the calculation of topological cross sections.

Contribution

It provides an overview of how to derive topological cross sections for hard processes on nuclei using nonlinear k_p-factorization, a new concept in pQCD.

Findings

Linear k_p-factorization breaks down in heavy nuclei.

Nonlinear k_p-factorization replaces linear factorization.

Method to obtain topological cross sections from nonlinear factorization.

Abstract

Heavy nuclei introduce a new scale into the pQCD description of hard processes on nuclei, the saturation scale, and the familiar linear k_\perp-factorization breaks down. It is replaced by a new concept, the nonlinear k_\perp-factorization. Here we give a brief overview how topological cross sections for hard processes on nuclei are obtained from nonlinear k_\perp-factorization.