Late-time cosmology of scalar-tensor theories with universal multiplicative coupling between the scalar field and the matter Lagrangian

Abstract

We investigate the late-time cosmological behaviour of scalar-tensor theories with a universal multiplicative coupling between the scalar field and the matter Lagrangian in the matter era. This class of theory encompasses the case of the massless string dilaton (see Damour and Polyakov, General Relativity and Gravitation, 26, 1171) as well as a theory with an intrinsic decoupling mechanism in the solar system (see Minazzoli and Hees, Phys. Rev. D 88, 041504). The cosmological evolution is studied in the General Relativity limit justified by solar system constraints on the gravitation theory. The behaviour of these cosmological evolutions are then compared to two types of observations: the constraints on temporal variations of the constants of Nature and the distance-luminosity measurements. In particular, the non-minimal coupling implies that the distance-luminosity relation is modified compared to General Relativity. Theories producing a cosmological behaviour in agreement with these observations are identified.