Acceleration of the Universe in Type-0 Non-Critical Strings: a Review

TL;DR

This review discusses how type-0 non-critical string theory models, involving D3 branes and fluxes, can explain the accelerated expansion of the universe consistent with current observations.

Contribution

It introduces a cosmological model based on type-0 non-critical strings with D3 branes, addressing tachyonic instabilities and matching astrophysical data.

Findings

Model is compatible with universe acceleration observations

The flux magnitude influences cosmological parameters

Tachyonic backgrounds are integral to the cosmological flow

Abstract

I review cosmology within the framework of type-0 non-critical strings, proposed in collaboration with G. Diamandis, B. Georgalas, E. Papantonopoulos and I. Pappa. The instabilities of the tachyonic backgrounds, due to the absence of space-time supersymmetry, are treated in this framework as a necessary ingredient to ensure cosmological flow. The model involves D3 brane worlds, whose initial quantum fluctuations induce the non criticality. I argue that this model is compatible with the current astrophysical observations pointing towards acceleration of the Universe. A crucial r\^ole for the correct ``phenomenology'' of the model, in particular the order-one value of the deceleration parameter, is played by the relative magnitude of the flux of the five form of the type-0 string as compared to the size of the volume of five of the extra dimensions, transverse to the direction of the flux-field.