Current Acceleration from Dilaton and Stringy Cold Dark Matter

TL;DR

This paper proposes a string theory-based model where the dilaton and stringy cold dark matter drive the universe's current acceleration, supported by analytical, numerical results, and supernovae data comparison.

Contribution

It introduces a novel cosmological scenario where the dilaton's coupling to stringy cold dark matter explains late-time acceleration, supported by analytical and numerical analysis.

Findings

Dilaton couples non-universally to stringy dark matter.

The model can reproduce observed acceleration.

Supernovae data favor certain stringy dark matter candidates.

Abstract

We argue that string theory has all the ingredients to provide us with candidates for the cold dark matter and explain the current acceleration of our Universe. In any generic string compactification the dilaton plays an important role as it couples to the Standard Model and other heavy non-relativistic degrees of freedom such as the string winding modes and wrapped branes, we collectively call them stringy cold dark matter. These couplings are non-universal which results in an interesting dynamics for a rolling dilaton. Initially, its potential can track radiation and matter while beginning to dominate the dynamics recently, triggering a phase of acceleration. This scenario can be realized as long as the dilaton also couples strongly to some heavy modes. We furnish examples of such modes. We provide analytical and numerical results and compare them with the current supernovae result. This favors certain stringy candidates.