2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/176587Recent astrophysical observations indicate that the proton-electron mass ratio and the fine structure constant have gone through nontrivial time evolution. We discuss their time variation in the context of a dilaton runaway scenario with gauge coupling unification at the string scale $M_{\rm s}$. We show that the choice of adjustable parameters allows them to fit the same order magnitude of both variations and their (opposite) signs in such a scenario.16 pages, 1 figure, to appear in Phys. Rev. DHigh Energy Physics - PhenomenologyAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext