The Slow Gravitino

TL;DR

This paper investigates how Lorentz symmetry breaking in a fluid background affects the gravitino's behavior, leading to non-relativistic dispersion relations and potential cosmological implications.

Contribution

It derives the modified equations of motion and propagator for the gravitino in a Lorentz-violating fluid background, revealing new non-relativistic properties.

Findings

Longitudinal gravitino mode has a subluminal dispersion relation

Lorentz violation alters the gravitino's helicity states and dynamics

Potential implications for gravitino cosmology and phenomenology

Abstract

When the supersymmetry breaking sector is a fluid background, Lorentz invariance is broken spontaneously. The super-Higgs mechanism leads to a gravitino Lagrangian with Lorentz symmetry violating terms. We analyse the resulting field equations and constraints. We identify the physical spin 3/2 and spin 1/2 helicity states, derive their equations of motion and construct the propagator. The violation of Lorentz symmetry implies that the longitudinal mode has a non-relativistic dispersion relation, whose speed is lower than the speed of light. We briefly comment on possible implications to gravitino cosmology and phenomenology.