Helicity Amplitudes for production of massive gravitino/goldstino

TL;DR

This paper extends the spinor helicity formalism to massive particles and applies it to compute decay amplitudes involving the gravitino and goldstino in a supersymmetric model, demonstrating its effectiveness.

Contribution

The paper develops the application of the spinor helicity formalism to massive particles and computes specific decay amplitudes involving gravitino and goldstino.

Findings

Successfully evaluated two-body neutralino decays involving massive gravitino and goldstino.

Showed the capability of the extended SHF in handling massive spin-3/2 and spin-1/2 particles.

Compared amplitudes for gravitino and goldstino, illustrating differences in their decay processes.

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.