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

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Authors

KLUSOŇ Josef CHACHIAN masud OKSANEN Markku TUREANU Anca

Year of publication 2014
Type Article in Periodical
Magazine / Source Journal of High Energy Physics (JHEP)
MU Faculty or unit

Faculty of Science

Citation
Doi http://dx.doi.org/10.1007/JHEP12(2014)102
Field Theoretical physics
Keywords Dark energy; Hamiltonian Formalism
Description 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 11 (2013) 135] 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.
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