Eur. Phys. J. C (2012) 72: 1889
https://doi.org/10.1140/epjc/s10052-012-1889-1

Special Article - Tools for Experiment and Theory

Automated one-loop calculations with GoSam

¹ DESY, Zeuthen, Germany
² School of Physics and Astronomy, The University of Edinburgh, Edinburgh, UK
³ Max-Planck-Institut für Physik, München, Germany
⁴ Department of Physics, University of Illinois at Urbana-Champaign, Urbana, USA
⁵ Institute for Particle Physics Phenomenology, University of Durham, Durham, UK
⁶ Dipartimento di Fisica, Università di Padova, Padova, Italy
⁷ New York City College of Technology, City University of New York, New York, USA
⁸ The Graduate School and University Center, City University of New York, New York, USA
⁹ CERN, Geneva, Switzerland

^* e-mail: gudrun@mpp.mpg.de

Received: 18 January 2012
Published online: 27 March 2012

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.