Eur. Phys. J. C (2011) 71: 1640
https://doi.org/10.1140/epjc/s10052-011-1640-3

Special Article - Tools for Experiment and Theory

HELAS and MadGraph with goldstinos

¹ Theoretische Natuurkunde and IIHE/ELEM, Vrije Universiteit Brussel, and International Solvay Institutes, Pleinlaan 2, 1050, Brussels, Belgium
² KEK Theory Center, and Sokendai, Tsukuba, 305-0801, Japan

^* e-mail: kentarou.mawatari@vub.ac.be

Received: 21 January 2011
Revised: 27 March 2011
Published online: 9 June 2011

Abstract

Fortran subroutines to calculate helicity amplitudes with goldstinos, which appear as the longitudinal modes of massive gravitinos in high energy processes, are added to the HELAS (HELicity Amplitude Subroutines) library. They are coded in such a way that arbitrary amplitudes with external goldstinos can be generated automatically by MadGraph, after slight modifications. All the codes have been tested carefully by making use of the goldstino equivalence theorem and the gauge invariance of the helicity amplitudes. Hadronic total cross sections for associated gravitino productions with a gluino and a squark are also presented.