Effective interactions of a light gravitino

TL;DR

This paper reviews recent findings on how a light gravitino interacts with ordinary particles, highlighting new aspects of low-energy theorems and discussing phenomenological implications like collider bounds.

Contribution

It introduces a novel feature of low-energy theorems for broken supersymmetry, showing additional free parameters in goldstino couplings not solely determined by the supersymmetry-breaking scale.

Findings

Bilinear goldstino terms are not fully controlled by the supersymmetry-breaking scale.

Additional free parameters appear in the effective lagrangian for goldstino couplings.

A lower bound on the gravitino mass is suggested from collider data.

Abstract

We review some recent results on the effective interactions of a light gravitino with ordinary particles. In particular, we discuss on a simple example a novel aspect of the low-energy theorems for broken supersymmetry: in the effective lagrangian describing the goldstino couplings to matter, there are terms bilinear in the goldstino that, already at the lowest non-trivial order, are not entirely controlled by the supersymmetry-breaking scale, and introduce additional free parameters. We conclude by mentioning some phenomenological implications, including a lower bound on the gravitino mass from collider data.