Composition-dependent long range forces from varying m(p)/m(e)

We relate possible cosmological variations in the mass ratio μ ≡ mp/me and the fine structure constant α to long range composition-dependent forces mediated by a scalar field. The differential acceleration η in Eotvos-type experiments is bounded below by 10−14, except in cases where one or more scalar couplings vanish. We consider what values for these couplings could arise from unified theories. By considering the contribution of the scalar field to the cosmological energy density we use bounds on η to put upper bounds on the current rate of change of μ and α.