Automated one-loop calculations: a proof of concept

TL;DR

This paper introduces an automated algorithm for one-loop amplitude calculations in particle physics, integrating existing tools to handle complex configurations efficiently, demonstrated on LHC processes.

Contribution

It presents a novel automated method combining OPP reduction with HELAC and CutTools for comprehensive one-loop amplitude computations.

Findings

Successfully computed all LHC subprocesses from 2007 Les Houches wish list

Demonstrated the algorithm's capability across various momentum, color, and helicity configurations

Validated the approach with consistent results for complex particle interactions

Abstract

An algorithm, based on the OPP reduction method, to automatically compute any one-loop amplitude, for all momentum, color and helicity configurations of the external particles, is presented. It has been implemented using the tree-order matrix element code HELAC and the OPP reduction code CutTools. As a demonstration of the potential of the current implementation, results for all sub-processes included in the 2007 Les Houches wish list for LHC, are presented.