Unitarity Method with Spurious Pole

TL;DR

This paper introduces a method to handle spurious poles in unitarity cut calculations, enabling explicit algebraic expressions for coefficients and providing a novel analytic result for a five-gluon one-loop amplitude.

Contribution

It presents a new approach to manage spurious poles in unitarity methods, improving the calculation of loop amplitudes with explicit algebraic formulas.

Findings

Explicit algebraic functions for coefficients with spurious poles

First analytic result for one-loop five-gluon amplitude with scalar propagator

Enhanced simplification in unitarity cut calculations

Abstract

In unitarity cut method, compact input of on-shell tree level amplitudes is crucial to simplify calculations. Although BCFW on-shell recursion relation gives very compact tree level amplitudes, they usually contain spurious poles. In this paper, we present a method to deal with this issue and provide explicit simple algebraic functions for various coefficients in the presence of spurious poles. As an application, we present analytic result (not just rational term) for one-loop five gluon A(-++++) with scalar propagator for the first time.