Bimetric Starobinsky model

Abstract

The bimetric theory of gravity is an extension of general relativity that describes a massive spin-$2$ particle in addition to the standard massless graviton. The theory is based on two dynamical metric tensors with their interactions constrained by requiring the absence of the so-called Boulware-Deser ghost. It has been realized that the quantum interactions of matter fields with gravity are bound to generate modifications to the standard Einstein-Hilbert action such as quadratic curvature terms. Such a quadratic Ricci scalar term is present in the so-called Starobinsky model which has been proven to be rather robust in its inflationary predictions. In the present article we study a generalization of the Starobinsky model within the bimetric theory and find that its inflationary behavior stays intact while keeping all consistency requirements of the bimetric framework. The interpretation of the massive spin-2 particle as dark matter remains a viable scenario, as in standard bigravity.

7 pages, 3 figures, title slightly edited, matches published version

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• On couplings to matter in massive (bi-)gravity
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• Oscillating Spin-2 Dark Matter
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Cited by in corpus (8)

• Angular correlation and deformed Hellings-Downs curve from spin-2 ultralight dark matter
• Static spheres and Aschenbach effect for black holes in massive gravity
• On the absence of ghosts in quadratic bigravity
• Nonlinear evolution of anisotropic matter configurations under higher-order curvature corrections
• Dynamically induced spin-2 mass in a Weyl-invariant framework
• Linearized Gravity in the Starobinsky Model: Perturbative Deviations from General Relativity
• Spherically Symmetric Potentials in Quadratic $f(R)$ Gravity
• Topological charge and black hole photon spheres in massive gravity