Initial conditions for the scalaron dark matter

Abstract The scalaron of the metric f ( R ) gravity can constitute dark matter if its mass is in range 4 meV ? m 1 MeV. We give an overview such theory minimally coupled to Standard Model. Similarly other dark-matter models based on scalar fields, this model has issue initial conditions. Firstly, conditions for are be tuned order produce observed amount matter. Secondly, primordial spatial inhomogeneities field sufficiently small because they generate entropy (or isocurvature) perturbations, which constrained by observations. consider these issues present paper. presumably emerge at inflationary stage. point out that homogeneous part value largely unpredictable quantum diffusion during inflation. Thus, account matter, one resort anthropic considerations. Observational constraints inhomogeneity translated into upper bounds energy scale inflation, happen low but not too restrictive.