Infrared safety of impact factors for colourless particle interactions

TL;DR

This paper proves that impact factors for colorless particle interactions in high-energy QCD processes are free of infrared singularities at next-to-leading order, ensuring theoretical consistency.

Contribution

It provides a general proof of infrared safety for impact factors in high-energy QCD, extending previous results to next-to-leading order accuracy.

Findings

Infrared singularities cancel at next-to-leading order

The proof applies generally, exemplified with virtual photon interactions

Ensures consistency of impact factor calculations in QCD

Abstract

We demonstrate, to next-to-leading order accuracy, the cancellation of the infrared singularities in the impact factors which arise in the QCD description of high energy processes A + B -> A' + B' of colourless particles. We study the example where A is a virtual photon in detail, but show that the result is true in general.