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Phys. Rev. D 70, 063521 (2004) [6 pages]

Oscillatory universes in loop quantum cosmology and initial conditions for inflation

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James E. Lidsey, David J. Mulryne, N. J. Nunes, and Reza Tavakol
Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS, United Kingdom

Received 18 June 2004; published 17 September 2004

Positively curved oscillatory universes are studied within the context of loop quantum cosmology subject to a consistent semiclassical treatment. The semiclassical effects are reformulated in terms of an effective phantom fluid with a variable equation of state. In cosmologies sourced by a massless scalar field, these effects lead to a universe that undergoes ever-repeating cycles of expansion and contraction. The presence of a self-interaction potential for the field breaks the symmetry of the cycles and can enable the oscillations to establish the initial conditions for successful slow-roll inflation, even when the field is initially at the minimum of its potential with a small kinetic energy. The displacement of the field from its minimum is enhanced for lower and more natural values of the parameter that sets the effective quantum gravity scale. For sufficiently small values of this parameter, the universe can enter a stage of eternal self-reproduction.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevD.70.063521
DOI:
10.1103/PhysRevD.70.063521
PACS:
98.80.Cq, 04.60.Pp