Degravitation of the Cosmological Constant in Bigravity

TL;DR

This paper explores how bigravity theories can suppress the gravitational effects of a large cosmological constant, potentially addressing the cosmological constant problem.

Contribution

It demonstrates degravitation of the cosmological constant within a ghost-free bigravity framework, highlighting a regime where gravitational effects are mild despite a large vacuum energy.

Findings

Degravitation occurs when the physical graviton is a gauge-invariant metric combination.

The theory remains ghost-free and consistent.

Several phenomenological implications are discussed.

Abstract

In this article the phenomenon of degravitation of the cosmological constant is studied in the framework of bigravity. It is demonstrated that despite a sizable value of the cosmological constant its gravitational effect can be only mild. The bigravity framework is chosen for this demonstration as it leads to a consistent, ghost-free theory of massive gravity. We show that degravitation takes place in the limit where the physical graviton is dominantly a gauge invariant metric combination. We present and discuss several phenomenological consequences expected in this regime.