Decomposition of BPS Moduli Spaces and Asymptotics of Supersymmetric Partition Functions

Abstract

We present a prototype for Wilsonian analysis of asymptotics of supersymmetric partition functions of non-abelian gauge theories. Localization allows expressing such partition functions as an integral over a BPS moduli space. When the limit of interest introduces a scale hierarchy in the problem, asymptotics of the partition function is obtained in the Wilsonian approach by \(i)\) decomposing (in some suitable scheme) the BPS moduli space into various patches according to the set of light fields (lighter than the scheme dependent cut-off \(\Lambda\)) they support, \(ii)\) localizing the partition function of the effective field theory on each patch (with cut-offs set by the scheme), and \(iii)\) summing up the contributions of all patches to obtain the final asymptotic result (which is scheme-independent and accurate as \(\Lambda\to\infty\)). Our prototype concerns the Cardy-like asymptotics of the 4d superconformal index, which has been of interest recently for its application to black hole microstate counting in AdS\(_5\)/CFT\(_4\). As a byproduct of our analysis we obtain the most general asymptotic expression for the index of gauge theories in the Cardy-like limit, encompassing and extending all previous results.