Trans-Planckian physics and the spectrum of fluctuations in a bouncing universe

Robert H. Brandenberger, Sergio E. Jorás, and Jérôme Martin
Phys. Rev. D 66, 083514 – Published 30 October 2002
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Abstract

In this paper, we calculate the spectrum of scalar field fluctuations in a bouncing, asymptotically flat universe, and investigate the dependence of the result on changes in the physics on length scales shorter than the Planck length which are introduced via modifications of the dispersion relation. In this model, there are no ambiguities concerning the choice of the initial vacuum state. We study an example in which the final spectrum of fluctuations depends sensitively on the modifications of the dispersion relation without needing to invoke complex frequencies. Changes in the amplitude and in the spectral index are possible, in addition to modulations of the spectrum. This strengthens the conclusions of previous work in which the spectrum of cosmological perturbations in expanding inflationary cosmologies was studied, and it was found that, for dispersion relations for which the evolution is not adiabatic, the predictions obtained for the spectrum of fluctuations are not robust towards changes in the dispersion relation.

  • Received 4 October 2001

DOI:https://doi.org/10.1103/PhysRevD.66.083514

©2002 American Physical Society

Authors & Affiliations

Robert H. Brandenberger* and Sergio E. Jorás

  • Department of Physics, Brown University, Providence, Rhode Island 02912

Jérôme Martin

  • Institut d’Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France

  • *Email address: rhb@het.brown.edu
  • Current address: Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21945-970, Brazil. Electronic address: joras@het.brown.edu
  • Electronic address: jmartin@iap.fr

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Vol. 66, Iss. 8 — 15 October 2002

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