Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations

@article{Hirano2017HealthyID,
  title={Healthy imperfect dark matter from effective theory of mimetic cosmological perturbations},
  author={Shin'ichi Hirano and Sakine Nishi and Tsutomu Kobayashi},
  journal={Journal of Cosmology and Astroparticle Physics},
  year={2017},
  volume={2017},
  pages={009 - 009}
}
We study the stability of a recently proposed model of scalar-field matter called mimetic dark matter or imperfect dark matter. It has been known that mimetic matter with higher derivative terms suffers from gradient instabilities in scalar perturbations. To seek for an instability-free extension of imperfect dark matter, we develop an effective theory of cosmological perturbations subject to the constraint on the scalar field's kinetic term. This is done by using the unifying framework of… 

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