Constraints on quintessence and new physics from fundamental constant
  Changes in the values of the fundamental constants mu, the proton to electron mass ratio, and alpha, the fine structure constant due to rolling scalar fields have been discussed both in the context of cosmology and in new physics such as Super Symmetry (SUSY) models. This article examines the changes in these fundamental constants in a particular example of such fields, freezing and thawing slow roll quintessence. Constraints are placed on the product of a cosmological quantity, w, the equation of state parameter, and the square of the coupling constants for mu and alpha with the field, zeta_x, x = mu,alpha, using the existing observational limits on the values of Delta x/x. Various examples of slow rolling quintessence models are used to further quantify the constraints. Some of the examples appear to be rejected by the existing data which strongly suggests that conformation to the values of the fundamental constants in the early universe is a standard test that should be applied to any cosmological model or suggested new physics. 
Rodger I. Thompson
astro-ph.CO hep-ph