Runaway dilaton and equivalence principle violations

TL;DR

This paper explores how a runaway dilaton, decoupling during cosmological evolution, could cause detectable violations of the equivalence principle and variations in fundamental constants, linking these effects to inflationary density fluctuations.

Contribution

It proposes a scenario where the dilaton's residual interactions relate to inflationary fluctuations and could lead to observable equivalence principle violations and changes in fundamental constants.

Findings

Residual dilaton interactions can be large enough for detection.

Runaway dilaton can induce measurable variations in fundamental constants.

Potential for near-future experiments to detect these effects.

Abstract

In a recently proposed scenario, where the dilaton decouples while cosmologically attracted towards infinite bare string coupling, its residual interactions can be related to the amplitude of density fluctuations generated during inflation, and are large enough to be detectable through a modest improvement on present tests of free-fall universality. Provided it has significant couplings to either dark matter or dark energy, a runaway dilaton can also induce time-variations of the natural "constants" within the reach of near-future experiments.