Nonsingular bouncing universes in loop quantum cosmology

Parampreet Singh, Kevin Vandersloot, and G. V. Vereshchagin
Phys. Rev. D 74, 043510 – Published 10 August 2006

Abstract

Nonperturbative quantum geometric effects in loop quantum cosmology (LQC) predict a ρ2 modification to the Friedmann equation at high energies. The quadratic term is negative definite and can lead to generic bounces when the matter energy density becomes equal to a critical value of the order of the Planck density. The nonsingular bounce is achieved for arbitrary matter without violation of positive energy conditions. By performing a qualitative analysis we explore the nature of the bounce for inflationary and cyclic model potentials. For the former we show that inflationary trajectories are attractors of the dynamics after the bounce implying that inflation can be harmoniously embedded in LQC. For the latter difficulties associated with singularities in cyclic models can be overcome. We show that nonsingular cyclic models can be constructed with a small variation in the original cyclic model potential by making it slightly positive in the regime where scalar field is negative.

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  • Received 12 June 2006

DOI:https://doi.org/10.1103/PhysRevD.74.043510

©2006 American Physical Society

Authors & Affiliations

Parampreet Singh* and Kevin Vandersloot

  • Institute for Gravitational Physics and Geometry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

G. V. Vereshchagin

  • ICRANet and ICRA, P.le della Repubblica 10, 65100 Pescara, Italy, and University of Rome “La Sapienza”, Physics Department, P.le A. Moro 5, 00185 Rome, Italy

  • *E-mail address: singh@gravity.psu.edu
  • E-mail address: kfvander@gravity.psu.edu
  • E-mail address: veresh@icra.it

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Issue

Vol. 74, Iss. 4 — 15 August 2006

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