On scale-free extensions of massive (bi-)gravity

Abstract

We discuss a scale-free model of bigravity, in which the mass parameter of the standard bigravity potential is promoted to a dynamical scalar field. This modification retains the ghost-free bigravity structure, in particular it remains free of the Boulware-Deser ghost. We investigate the theory's interaction structure, focusing on its consistent scaling limits and strong coupling scales. Furthermore we explore the model's quadratic action, both around generic background configurations and paying special attention to cosmological backgrounds and to the associated background evolution. Finally we consider the possibility of realizing a phase of late-time acceleration as well as a quasi-de Sitter inflationary stage at early times, when the promoted "mass scalar" becomes the inflaton.

36 pages; v2 clarifying comments added, references updated, results unchanged

References in corpus (8)

• Resummation of Massive Gravity
• Interacting Spin-2 Fields
• Quantum scale invariance, cosmological constant and hierarchy problem
• Scale invariance, unimodular gravity and dark energy
• On couplings to matter in massive (bi-)gravity
• Cosmological perturbations in massive bigravity
• Gravitational waves in bigravity cosmology
• The coupling to matter in Massive, Bi- and Multi-Gravity