Cosmology with modified continuity equation in asymptotically safe gravity

Abstract

We study FLRW cosmology, taking into account quantum gravitational corrections in the formalism of the exact renormalization group flow of the effective action for gravity. We calculate the quantum corrected scale factor, energy density, and entropy production at late times, taking different choices of cut-off functions. Our approach is in line with previous studies which involve the running Newton constant G(k) in the definition of energy–momentum tensor, and then imposing the covariant conservation identity of the Einstein tensor. The quantum corrections obtained in this approach are different from what are found by letting the conservation equation remain the same as for a scale-independent Newton constant. The main observation made here is that different cut-off identifications results in different late time cosmologies. Further, the choices made also led to exact analytical solutions for the Hubble parameter in terms of the cosmological time and scale factor.