Bouncing and cyclic string gas cosmologies

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.

35 pages, LaTeX, 9 figures. v2: additional references. v3: comments on Einstein frame, version to appear in PRD

References in corpus (9)

• String Gas Cosmology and Structure Formation
• Non-perturbative Gravity, Hagedorn Bounce & CMB
• The Ups and Downs of Cyclic Universes
• On the new string theory inspired mechanism of generation of cosmological perturbations
• A Short Review of Time Dependent Solutions and Space-like Singularities in String Theory
• The Effect of alpha' Corrections in String Gas Cosmology
• Geometric Precipices in String Cosmology
• Speed of Sound in String Gas Cosmology
• Emergence of a Cyclic Universe from the Hagedorn Soup

Cited by in corpus (6)

• Towards a Resolution of the Cosmological Singularity in Non-local Higher Derivative Theories of Gravity
• Induced superstring cosmologies and moduli stabilization
• Non-singular string cosmology in a 2d Hybrid model
• Marginal Deformations of Vacua with Massive boson-fermion Degeneracy Symmetry
• Newtonian Potential and Geodesic Completeness in Infinite Derivative Gravity
• Antisymmetric field in string gas cosmology