Time variation of fundamental couplings and dynamical dark energy

TL;DR

This paper investigates how scalar fields could cause variations in fundamental constants over time, linking cosmological data with tests of the Weak Equivalence Principle to constrain such variations and explore specific models of scalar evolution.

Contribution

It combines cosmological and experimental data to constrain the time variation of fundamental constants and analyzes specific scalar field models like crossover quintessence.

Findings

Bounds on current coupling variation rates from experiments.

Comparison of sensitivity among different experimental methods.

Analysis of scalar evolution models such as crossover quintessence.

Abstract

Scalar field dynamics may give rise to a nonzero cosmological variation of fundamental constants. Within different scenarios based on the unification of gauge couplings, the various claimed observations and bounds may be combined in order to trace or restrict the time history of the couplings and masses. If the scalar field is responsible for a dynamical dark energy or quintessence, cosmological information becomes available for its time evolution. Combining this information with the time variation of couplings, one can determine the interaction strength between the scalar and atoms, which may be observed by tests of the Weak Equivalence Principle. We compute bounds on the present rate of coupling variation from experiments testing the differential accelerations for bodies with equal mass and different composition and compare the sensitivity of various methods. In particular, we discuss two specific models of scalar evolution: crossover quintessence and growing neutrino models.