2009

Scale-invariant cosmological perturbations from Horava-Lifshitz gravity without inflation

Mukohyama, Shinji

Understand

Based on the renormalizable theory of gravitation recently proposed by Horava, we present a simple scenario to generate almost scale-invariant, super-horizon curvature perturbations.

  • The anisotropic scaling with dynamical critical exponent z=3 implies that the amplitude of quantum fluctuations of a free scalar field generated in the early epoch of the expanding universe is insensitive to the Hubble expansion rate and, thus, scale-invariant.
  • Those fluctuations are later converted to curvature perturbations by the curvaton mechanism or/and the modulated decay of heavy particles/oscillating fields.
  • This scenario works, for example, for power law expansion a\propto t^p with p>1/3 and, thus, does not require inflation.

Built on

  • D. H. Lyth and D. Wands, “Generating the curvature perturbation without an inflaton,” Phys. Lett. B 524

    2002

    Earlier work this paper cites.

  • K. Enqvist and M. S. Sloth, “Adiabatic CMB perturbations in pre big bang string cosmology,” Nucl. Phys. B 626

    2002

    Earlier work this paper cites.

Similar

Then

  • N. Arkani-Hamed, P. Creminelli, S. Mukohyama and M. Zaldarriaga, “Ghost Inflation,” JCAP 0404

    2004

    Later among the works it cites.

  • G. Dvali, A. Gruzinov and M. Zaldarriaga, “A new mechanism for generating density perturbations from inflation,” Phys. Rev. D 69

    2004

    Later among the works it cites.

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