Two-loop amplitude generation in OpenLoops

TL;DR

This paper introduces a new algorithm for efficiently computing tensor coefficients in two-loop amplitudes, advancing the automation of NNLO calculations in particle physics.

Contribution

It presents a generic numerical algorithm for tensor coefficient construction crucial for automated NNLO amplitude generation.

Findings

Enables efficient numerical construction of tensor coefficients.

Facilitates automation of NNLO scattering amplitude calculations.

Supports high-precision theoretical predictions for particle physics experiments.

Abstract

Numerical tools, such as OpenLoops, provide NLO scattering amplitudes for a very wide range of hard scattering amplitudes in a fully automated way. In order to match the numerical precision of current and future experiments, however, the higher precision of NNLO calculations is essential, and their automation in a similar tool highly desirable. In our approach, D-dimensional amplitudes are decomposed into loop-momentum tensor integrals with coefficients constructed in four dimensions and rational terms. We present a fully generic algorithm for the efficient numerical construction of the tensor coefficients, which constitutes an important building block for an automated NNLO tool.