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Title:
Bouncing and cyclic string gas cosmologies
Authors:
Greene, Brian; Kabat, Daniel; Marnerides, Stefanos
Affiliation:
AA(Institute for Strings, Cosmology and Astroparticle Physics and Department of Physics, Columbia University, New York, New York 10027, USA), AB(Institute for Strings, Cosmology and Astroparticle Physics and Department of Physics, Columbia University, New York, New York 10027, USA; Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, New York 10468, USA), AC(Institute for Strings, Cosmology and Astroparticle Physics and Department of Physics, Columbia University, New York, New York 10027, USA)
Publication:
Physical Review D, vol. 80, Issue 6, id. 063526 (PhRvD Homepage)
Publication Date:
09/2009
Origin:
APS
Keywords:
Particle-theory and field-theory models of the early Universe, Strings and branes
PACS Keywords:
Particle-theory and field-theory models of the early Universe, Strings and branes
DOI:
10.1103/PhysRevD.80.063526
Bibliographic Code:
2009PhRvD..80f3526G

Abstract

We show that, in the presence of a string gas, simple higher-derivative modifications to the effective action for gravity can lead to bouncing and cyclic cosmological models. The modifications bound the expansion rate and avoid singularities at finite times. In these models the scale factors can have long loitering phases that solve the horizon problem. Adding a potential for the dilaton gives a simple realization of the pre-big bang scenario. Entropy production in the cyclic phase drives an eventual transition to a radiation-dominated Universe. As a test of the Brandenberger-Vafa scenario, we comment on the probability of decompactifying three spatial dimensions in this class of models.
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