Controlled Analytic Properties and the Quantitative Baum-Connes Conjecture

Abstract

We show that the classical Baum-Connes assembly map is quantitatively an isomorphism for a class of lacunary hyperbolic groups, and we explain how to see that this class contains many examples of groups that contain graph sequences of large girth inside their Cayley graphs and therefore do not have property (A). This includes the known counterexamples to the Baum-Connes conjecture with coefficients, as well as many other monster groups that have property (T).