Nonlinear Partially Massless from Massive Gravity?

TL;DR

This paper demonstrates that nonlinear partially massless models cannot be derived from standard massive gravity frameworks due to fundamental constraints, and it explores the limitations and acausality issues in these models.

Contribution

It shows the fundamental obstruction preventing the extension of linear partially massless theories to nonlinear regimes within f-g massive gravity.

Findings

Nonlinear partially massless models are incompatible with f-g massive gravity.

The fifth constraint responsible for ghost removal also blocks gauge invariance extension.

The study advances understanding of acausal f-g models and their limitations.

Abstract

We show that consistent nonlinear Partially Massless models cannot be obtained starting from "f-g" massive gravity, with "f" the embedding de Sitter space. The obstruction, which is also the source of f-g acausality, is the very same fifth constraint that removes the notorious sixth ghost excitation. Here, however, it blocks extension of the mass to cosmological background tuned gauge invariance that took away the helicity zero mode at linear level. Separately, our methods allow us to almost complete the class of acausal f-g models.