The Spectrum of Goldstini and Modulini

TL;DR

This paper analyzes the mass spectrum of multiple goldstini in theories with various supersymmetry breaking mechanisms, revealing specific mass relations and the conditions for massless modulini, with implications for collider and cosmological phenomenology.

Contribution

It provides a comprehensive tree-level analysis of goldstini masses in mixed F-term, D-term, and no-scale breaking scenarios using non-linear superfields and a new supergravity gauge fixing.

Findings

Goldstini have a mass twice the gravitino mass in F-term and D-term breaking.

The modulino remains massless in no-scale breaking scenarios.

The massless modulino is linked to an accidental global supersymmetry.

Abstract

When supersymmetry is broken in multiple sectors via independent dynamics, the theory furnishes a corresponding multiplicity of "goldstini" degrees of freedom which may play a substantial role in collider phenomenology and cosmology. In this paper, we explore the tree-level mass spectrum of goldstini arising from a general admixture of F-term, D-term, and almost no-scale supersymmetry breaking, employing non-linear superfields and a novel gauge fixing for supergravity discussed in a companion paper. In theories of F-term and D-term breaking, goldstini acquire a mass which is precisely twice the gravitino mass, while the inclusion of no-scale breaking renders one of these modes, the modulino, massless. We argue that the vanishing modulino mass can be explained in terms of an accidental and spontaneously broken "global" supersymmetry.