SWISS-CHEESE COSMOLOGIES WITH VARIABLE G AND Λ FROM THE RENORMALIZATION GROUP

Abstract

A convincing explanation for the nature of the dark energy and dark matter is still missing. In recent works a RG-improved swiss-cheese cosmology with an evolving cosmological constant dependent on the Schücking radius has been proven to be a promising model to explain the observed cosmic acceleration. In this work we extend this model to consider the combined scaling of the Newton constant G and the cosmological constant Λ according to the IR-fixed point hypothesis. We shall show that our model easily generates the observed recent passage from deceleration to acceleration without need of extra energy scales, exotic fields or fine-tuning. In order to check the generality of the concept, two different scaling relations have been analyzed and we proved that both are in very good agreement with Λ CDM cosmology while one of them has no fine-tuning problem. We also show that our model satisfies the observational local constraints on ˙ G / G .