A class of renormalization group invariant scalar field cosmologies

We present a class of scalar field cosmologies with a dynamically evolving Newton parameter G and cosmological term Lambda. In particular, we discuss a class of solutions which are consistent with a renormalization group scaling for G and Lambda near a fixed point. Moreover, we propose a modified action for gravity which includes the effective running of G and Lambda near the fixed point. A proper understanding of the associated variational problem is obtained upon considering the four-dimensional gradient of the Newton parameter.