A spectre is haunting the cosmos: Quantum stability of massive gravity with ghosts

Abstract

Many theories of modified gravity with higher order derivatives are usually ignored because of serious problems that appear due to an additional ghost degree of freedom. Most dangerously, it causes an immediate decay of the vacuum. However, breaking Lorentz invariance can cure such abominable behavior. By analyzing a model that describes a massive graviton together with a remaining Boulware-Deser ghost mode we show that even ghostly theories of modified gravity can yield models that are viable at both classical and quantum levels and, therefore, they should not generally be ruled out. Furthermore, we identify the most dangerous quantum scattering process that has the main impact on the decay time and find differences to simple theories that only describe an ordinary scalar field and a ghost. Additionally, constraints on the parameters of the theory including some upper bounds on the Lorentz-breaking cutoff scale are presented. In particular, for a simple theory of massive gravity we find that a breaking of Lorentz invariance is allowed to happen even at scales above the Planck mass. Finally, we discuss the relevance to other theories of modified gravity.

18 pages, 3 figures, version published in JHEP

References in corpus (5)

• Resummation of Massive Gravity
• Beyond $\Lambda$CDM: Problems, solutions, and the road ahead
• Avoiding Dark Energy with 1/R Modifications of Gravity
• Living with ghosts in Horava-Lifshitz gravity
• On the naturalness of Einstein's equation

Cited by in corpus (12)

• Graviton Mass Bounds
• Dark Energy in light of Multi-Messenger Gravitational-Wave astronomy
• Neutron star merger GW170817 strongly constrains doubly coupled bigravity
• Non-minimal Derivative Coupling Scalar Field and Bulk Viscous Dark Energy
• Muon anomalous magnetic moment in the standard model extension
• On nonlocally interacting metrics, and a simple proposal for cosmic acceleration
• The Integrated Sachs-Wolfe Effect in the Bulk Viscous Dark Energy Model
• Searching for dark energy in the matter-dominated era
• Cosmological Instabilities and the Role of Matter Interactions in Dynamical Dark Energy Models
• Probing Lorentz violation effects via a laser beam interacting with a high-energy charged lepton beam
• Lorentz violation parameters and noncommutative scale
• Cherenkov radiation as ghost instability