Pseudo-Linear Spin-2 Interactions

TL;DR

This paper extends pseudo-linear interactions for spin-2 particles to multiple fields, creating ghost-free bi- and multi-gravity analogues with novel gauge symmetry properties and connections to higher-dimensional theories.

Contribution

It introduces a straightforward extension of pseudo-linear spin-2 interactions to multiple fields, including massless and massive cases, avoiding ghosts and linking to higher-dimensional theories.

Findings

Extended pseudo-linear interactions to multiple spin-2 fields.

Constructed ghost-free bi- and multi-gravity analogues.

Identified gauge invariance properties and higher-dimensional connections.

Abstract

We show how the pseudo-linear interactions for spin-2 particles can be straightforwardly extended to include multiple massive and massless fields without introducing ghosts. When massive spin-2 fields are included, these give simple analogues of bi-gravity and multi-gravity theories with mass terms that break linear gauge symmetries. The interactions containing only massless particles cannot be written in terms of linearized curvature tensors and are gauge invariant only up to a total derivative. These correspond to known theories that exist in more than four dimensions and evade the no-go results on interacting massless spin-2 particles.