Effective theory of interacting dark energy

@article{Gleyzes2015EffectiveTO,
  title={Effective theory of interacting dark energy},
  author={J'erome Gleyzes and David Langlois and Michele Mancarella and Filippo Vernizzi},
  journal={Journal of Cosmology and Astroparticle Physics},
  year={2015},
  volume={2015},
  pages={054 - 054}
}
We present a unifying treatment of dark energy and modified gravity that allows distinct conformal-disformal couplings of matter species to the gravitational sector. In this very general approach, we derive the conditions to avoid ghost and gradient instabilities. We compute the equations of motion for background quantities and linear perturbations. We illustrate our formalism with two simple scenarios, where either cold dark matter or a relativistic fluid is nonminimally coupled. This extends… 

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