Consistent Bimetric Theory and its Application to Cosmology

TL;DR

This paper discusses a ghost-free bimetric theory involving two metrics, which can model the universe's expansion without dark energy, offering a consistent framework for massive spin-2 fields.

Contribution

It presents a consistent, ghost-free bimetric theory that successfully reproduces cosmological expansion history without vacuum energy input.

Findings

Reproduces universe expansion history without dark energy

Provides a ghost-free formulation for massive spin-2 interactions

Offers a new approach to classical field theory problems

Abstract

Recently, the construction of ghost-free nonlinear massive spin-2 interactions solved a long outstanding problem in classical field theory. The consistent formulation requires a second rank-two tensor (or metric) and therefore has the form of a bimetric theory. Besides providing the solution to an old problem in field theory, ghost-free bimetric theory also has an interesting phenomenology: Its homogeneous and isotropic background solutions can reproduce the expansion history of the universe without any input of vacuum energy.