Nonlinear Partially Massless from Massive Gravity?

Understand

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.