Cosmic Acceleration and the String Coupling

TL;DR

This paper links the universe's late-time acceleration to the square of the string coupling in a cosmological string model, proposing a way to measure string coupling directly from cosmological data.

Contribution

It demonstrates that cosmic acceleration can be directly related to the string coupling in non-critical string models with a linear dilaton background, offering a novel observational approach.

Findings

Cosmic acceleration equals the square of the string coupling.

String coupling can be measured through cosmological observations.

The relation is specific to non-critical string models with a linear dilaton.

Abstract

In the context of a cosmological string model describing the propagation of strings in a time-dependent Robertson-Walker background space-time, we show that the asymptotic acceleration of the Universe can be identified with the square of the string coupling. This allows for a direct measurement of the ten-dimensional string coupling using cosmological data. We conjecture that this is a generic feature of a class of non-critical string models that approach asymptotically a conformal (critical) sigma model whose target space is a four-dimensional space-time with a dilaton background that is linear in sigma-model time. The relation between the cosmic acceleration and the string coupling does not apply in critical strings with constant dilaton fields in four dimensions.