Environmental dependence of masses and coupling constants

Abstract

We construct a class of scalar field models coupled to matter that lead to the dependence of masses and coupling constants on the ambient matter density. Such models predict a deviation of couplings measured on the Earth from values determined in low-density astrophysical environments, but do not necessarily require the evolution of coupling constants with the redshift in the recent cosmological past. Additional laboratory and astrophysical tests of $\ensuremath{\Delta}\ensuremath{\alpha}$ and $\ensuremath{\Delta}({m}_{p}/{m}_{e})$ as functions of the ambient matter density are warranted.