Cosmological Evolution in a Type-0 String Theory

TL;DR

This paper investigates the evolution of a universe derived from type-0 string theory, showing inflation, stabilization of extra dimensions, and a transition to a non-accelerating expansion with a relaxing vacuum energy.

Contribution

It introduces a novel cosmological model from type-0 string theory with non-criticality and demonstrates inflation, stabilization, and late-time acceleration behaviors.

Findings

Universe exhibits inflation and graceful exit.

Extra dimensions are stabilized with the fifth dimension larger.

Late-time universe is linearly expanding with relaxing vacuum energy.

Abstract

We study the cosmological evolution of a type-0 string theory by employing non-criticality, which may be induced by fluctuations of the D3 brane worlds. We check the consistency of the approach to O(alpha ') in the corresponding sigma-model. The ten-dimensional theory is reduced to an effective four-dimensional model, with only time dependent fields. We show that the four-dimensional universe has an inflationary phase and graceful exit from it, while the other extra dimensions are stabilized to a constant value, with the fifth dimension much larger than the others. We pay particular attention to demonstrating the role of tachyonic matter in inducing these features. The Universe asymptotes, for large times, to a non-accelerating linearly-expanding Universe with a time-dependent dilaton and a relaxing to zero vacuum energy a la quintessence.