Prediction for the cosmological constant in resummed quantum gravity and constraints on susy GUTs

We use our resummed quantum gravity approach to Einstein's general theory of relativity in the context of the Planck scale cosmology formulation of Bonanno and Reuter to estimate the value of the cosmological constant such that rho(Lambda) = (0.0024 eV)(4). We argue that the closeness of this estimate to experiment constrains Supersymmetric Grand Unified Theory (susy GUT) models. We discuss in turn various theoretical issues that have been raised about the approach itself as well as about the application to estimate the cosmological constant. Given the closeness of the estimate to the currently observed value, we also discuss the theoretical uncertainty in the estimate-at this time, we argue it is still large.