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 Sch\"ucking 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 $\mathrm{\ensuremath{\Lambda}}$ 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 $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ cosmology while one of them has no fine-tuning problem. We also show that our model satisfies the observational local constraints on $\stackrel{\ifmmode \dot{}\else \textperiodcentered \fi{}}{G}/G$.

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