On (in)stabilities of perturbations in mimetic models with higher derivatives
Abstract
Usually when applying the mimetic model to the early universe, higher derivative terms are needed to promote the mimetic field to be dynamical. However such models suffer from the ghost and/or the gradient instabilities and simple extensions cannot cure this pathology. We point out in this paper that it is possible to overcome this difficulty by considering the direct couplings of the higher derivatives of the mimetic field to the curvature of the spacetime.
- Publication:
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Journal of Cosmology and Astroparticle Physics
- Pub Date:
- August 2017
- DOI:
- 10.1088/1475-7516/2017/08/040
- arXiv:
- arXiv:1704.06834
- Bibcode:
- 2017JCAP...08..040Z
- Keywords:
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- General Relativity and Quantum Cosmology;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- High Energy Physics - Theory
- E-Print:
- 10 pages, 1 figure, the version accepted by JCAP