Helicity Amplitudes for production of massive gravitino/goldstino

Abstract

The spinor helicity formalism (SHF) has been efficiently applied to compute perturbative amplitudes in plenty of processes and reactions in gauge theories (including gravity), mostly in the massless case. Some work has been done in order to extend the SHF to the massive case. We have used these powerful tools to evaluate amplitudes in a local supersymmetric model where the gravitino is the lightest supersymmetric particle (LSP). Two decays have been evaluated in order to show the capability of the SHF in the massive extension, namely the two body neutralino decays $\tilde{\chi}_0\to V\tilde{\Psi}^{\mu}$ with $V=\gamma, Z$. The comparisons of amplitudes with spin-3/2 gravitino and spin-1/2 goldstino are also presented.