Mimetic dark matter, ghost instability and a mimetic tensor-vector-scalar gravity

Abstract

Recently modified gravitational theories which mimic the behaviour of dark matter, the so-called "Mimetic Dark Matter", have been proposed. We study the consistency of such theories with respect to the absence of ghost instability and propose a new tensor-vector-scalar theory of gravity, which is a generalization of the previous models of mimetic dark matter with additional desirable features. The original model proposed by Chamseddine and Mukhanov [JHEP 1311 (2013) 135, arXiv:1308.5410] is concluded to describe a regular pressureless dust, presuming that we consider only those configurations where the energy density of the mimetic dust remains positive under time evolution. For certain type of configurations the theory can become unstable. Both alternative modified theories of gravity, which are based on a vector field (tensor-vector theory) or a vector field and a scalar field (tensor-vector-scalar theory), are free of ghost instabilities.

23 pages, v4: clarifies and/or extends the discussion on the positivity of total energy, the instability found in the original mimetic model, and the number of physical degrees of freedom in each considered theory. Presentation improved in section 3. To be published in J. High Energy Phys

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Cited by in corpus (10)

• Mimetic gravity: a review of recent developments and applications to cosmology and astrophysics
• Dynamical behavior in mimetic F(R) gravity
• Imperfect Dark Matter
• Higher Derivative Mimetic Gravity
• Late time cosmological approach in mimetic $f(R,T)$ gravity
• Hamiltonian Formulation of Mimetic Gravity
• Black hole solutions in mimetic Born-Infeld gravity
• Forms of action for perfect fluid in General Relativity and mimetic gravity
• Primordial Cosmology in Mimetic Born-Infeld Gravity
• Direct couplings of mimetic dark matter and their cosmological effects