Higgs for Graviton: Simple and Elegant Solution

TL;DR

The paper tackles the problem of constructing a ghost-free, unitary theory of a massive graviton in four dimensions via a Higgs mechanism. It introduces four scalar fields φ^A with a global Lorentz symmetry in field space and an explicit diffeomorphism- and Lorentz-invariant action, yielding a FP mass term when symmetry is broken and five degrees of freedom for the graviton; in the unbroken phase the graviton remains massless and interacts with the scalars without propagating ghosts at linear order. The approach also discusses tuning of the cosmological constant, showing that with appropriate parameter choices the background can be Minkowski or de Sitter/anti-de Sitter-like, linking to potential cosmological implications. Overall, the framework provides a simple, ghost-free Higgs mechanism for graviton mass and offers a plausible route to modified gravity with possible relevance to dark energy.

Abstract

A Higgs mechanism for gravity is presented, where four scalars with global Lorentz symmetry are employed. We show that in the broken symmetry phase a graviton absorbs all scalars and become massive spin 2 particle with five degrees of freedom. The resulting theory is unitary and free of ghosts.