Light-by-light scattering at three loops in massless QCD and QED: amplitudes and cross sections

TL;DR

This paper computes three-loop helicity amplitudes for light-by-light scattering in massless QCD and QED, providing compact analytic results and NNLO cross-section predictions that agree with experimental data from ATLAS.

Contribution

It presents the first three-loop massless QCD and QED helicity amplitudes for light-by-light scattering with compact analytic expressions and their application to NNLO cross-section predictions.

Findings

Analytic amplitudes are compact and efficiently evaluable.

NNLO predictions agree with ATLAS experimental data.

Provides a new theoretical framework for light-by-light scattering analysis.

Abstract

We present the calculation of three-loop massless QCD and QED helicity amplitudes for light-by-light scattering. We make use of Lorentz tensor decomposition in the 't Hooft-Veltman dimensional regularisation scheme to reduce the complexity of the computation. Our analytic amplitude results are remarkably compact and can be efficiently evaluated numerically. We employ them to compute the corresponding NNLO differential cross-section predictions in the invariant mass and rapidity distributions of the di-photon system, for which we find agreement with the experimental ATLAS data from ultra-peripheral heavy-ion collisions.