Colourful FKS subtraction

TL;DR

This paper presents a colour-friendly formulation of the FKS subtraction method for calculating QCD cross sections at NLO, utilizing colour flows and expansions in 1/N for improved organization and accuracy.

Contribution

It introduces a novel colour-friendly approach to FKS subtraction, leveraging colour flows and 1/N expansion for systematic and exact calculations.

Findings

Exact to all orders in N using colour flows

Systematic expansion in 1/N improves organization

Applicable to next-to-leading order QCD calculations

Abstract

I formulate in a colour-friendly way the FKS method for the computation of QCD cross sections at the next-to-leading order accuracy. This is achieved through the definition of subtraction terms for squared matrix elements, constructed with single colour-dressed or pairs of colour-ordered amplitudes. The latter approach relies on the use of colour flows, is exact to all orders in $N$, and is thus particularly suited to being organized as a systematic expansion in 1/N.