One-Loop Splitting Amplitudes in Gauge Theory

TL;DR

The paper targets the universal infrared structure of one-loop gauge-theory amplitudes in soft and collinear limits, focusing on the collinear factorization described by splitting amplitudes. It employs a unitarity-based method to recompute these one-loop functions, presenting results in a form ready for incorporation into two-loop calculations. Additionally, it provides a compact function that captures the one-loop behavior in both soft and collinear regimes. These contributions enhance the precision toolkit for higher-order QCD computations and cross-checks of multi-leg amplitudes.

Abstract

We recompute the functions describing the collinear factorization of one-loop amplitudes using the unitarity-based method. We present the results in a form suitable for use as an ingredient in two-loop calculations. We also present a function summarizing the behavior at one loop in both the soft and collinear limits.