Competing bounds on the present-day time variation of fundamental constants

TL;DR

This paper compares various experimental bounds on the current variation of fundamental constants, highlighting the dependence on theoretical assumptions and the potential implications for dark energy and particle physics.

Contribution

It provides a comprehensive comparison of bounds from different methods and discusses how their relative sensitivities depend on underlying theoretical models.

Findings

WEP tests currently provide the most sensitive bounds within unified scenarios.

Detection of variation in atomic clocks would support dynamical dark energy models.

Sensitivity depends on relations between variations of different couplings in the standard model.

Abstract

We compare the sensitivity of a recent bound on time variation of the fine structure constant from optical clocks with bounds on time varying fundamental constants from atomic clocks sensitive to the electron-to-proton mass ratio, from radioactive decay rates in meteorites, and from the Oklo natural reactor. Tests of the Weak Equivalence Principle also lead to comparable bounds on present variations of constants. The "winner in sensitivity" depends on what relations exist between the variations of different couplings in the standard model of particle physics, which may arise from the unification of gauge interactions. WEP tests are currently the most sensitive within unified scenarios. A detection of time variation in atomic clocks would favour dynamical dark energy and put strong constraints on the dynamics of a cosmological scalar field.