Analytical On-shell Calculation of Higher Order Scattering: Massless Particles

TL;DR

This paper introduces an on-shell method leveraging t-channel discontinuities to efficiently compute higher-order electromagnetic and gravitational scattering amplitudes involving massless particles, simplifying previous complex calculations.

Contribution

It presents a novel on-shell approach for calculating loop contributions in scattering processes, streamlining higher-order results for massless and massive particles in gravity and electromagnetism.

Findings

Simplified calculation of higher-order gravitational scattering

Efficient evaluation of electromagnetic scattering loops

Reduction of complex Feynman diagram computations

Abstract

We demonstrate that the use of on-shell methods involving calculation of the discontinuity across the t-channel cut associated with the exchange of a pair of massless particles can be used to evaluate loop contributions to the electromagnetic and gravitational scattering of both massive and massless particles. In the gravitational case the use of factorization permits a straightforward and algebraic calculation of higher order scattering results, which were obtained previously by considerably more arduous Feynman diagram techniques.