%0 Journal Article %T A renormalized Perelman-functional and a lower bound for the ADM-mass %A Robert Haslhofer %J Mathematics %D 2011 %I arXiv %R 10.1016/j.geomphys.2011.06.016 %X In the first part of this short article, we define a renormalized F-functional for perturbations of non-compact steady Ricci solitons. This functional motivates a stability inequality which plays an important role in questions concerning the regularity of Ricci-flat spaces and the non-uniqueness of the Ricci flow with conical initial data. In the second part, we define a geometric invariant lambda_AF for asymptotically flat manifolds with nonnegative scalar curvature. This invariant gives a quantitative lower bound for the ADM-mass from general relativity, motivates a Ricci flow proof of the rigidity statement in the positive mass theorem, and eventually leads to the discovery of a mass decreasing flow in dimension three. %U http://arxiv.org/abs/1101.1226v2