Gevrey Regularity and Compact Quantum Metric Spaces for $L^p$-Group Algebras

Abstract

We introduce the beta-Gevrey lp-rapid decay property (GRD){beta,p}, for 0 < beta <= 1 and 1 <= p < infinity, for countable discrete groups. This property is a subexponential analogue of classical rapid decay, in which polynomial control is replaced by logarithmic subexponential control of order o(R^beta). We establish basic results for (GRD){beta,p}. We then apply this framework to compact quantum metric structures on reduced Lp-group algebras. We introduce strongly dense-core beta-Gevrey regular lp-spectral triples and give two classes of examples. For countable discrete groups satisfying (GRD)_{beta,p}, we prove, using Rieffel&#39;s criterion, that the corresponding Gevrey seminorms induce metrics on the Banach-algebra state space which metrize the weak-* topology. This yields compact quantum metric space structures in settings beyond classical rapid decay, including groups of intermediate growth such as the first Grigorchuk group.