Evolution of the fine-structure constant in runaway dilaton models

We study the detailed evolution of the fine-structure constant $α$ in the string-inspired runaway dilaton class of models of Damour, Piazza and Veneziano. We provide constraints on this scenario using the most recent $α$ measurements and discuss ways to distinguish it from alternative models for varying $α$. For model parameters which saturate bounds from current observations, the redshift drift signal can differ considerably from that of the canonical $Λ$CDM paradigm at high redshifts. Measurements of this signal by the forthcoming European Extremely Large Telescope (E-ELT), together with more sensitive $α$ measurements, will thus dramatically constrain these scenarios.

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