Automated One-Loop Calculations with GoSam

TL;DR

GoSam is an automated software package that efficiently computes one-loop amplitudes for complex multi-particle processes in quantum field theories, supporting both Standard Model and Beyond Standard Model calculations.

Contribution

It introduces a flexible, automated tool for calculating one-loop amplitudes with multiple reduction methods, applicable to a wide range of particle physics processes.

Findings

Successfully computed processes with up to six external legs.

Supports both QCD and electroweak corrections.

Links to models beyond the Standard Model.

Abstract

We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop.