The asymptotic growth of states of the 4d N=1 superconformal index
Alejandro Cabo-Bizet, Davide Cassani, Dario Martelli, Sameer Murthy
TL;DR
This work demonstrates that the four-dimensional ${\cal N}=1$ superconformal index exhibits exponential growth in charges in a Cardy-like limit, matching the Bekenstein-Hawking entropy of supersymmetric AdS$_5$ black holes. It achieves this via two complementary saddle-point analyses: a finite-$N$ Cardy-like limit and a large-$N$ saddle-point approach, both of which identify a universal saddle at vanishing gauge holonomies controlled by anomaly data ${\rm Tr}R$ and ${\rm Tr}R^3$, and express the leading behavior in terms of central charges $a,c$. For ${\cal N}=4$ SYM and a broad class of ${\cal N}=1$ quivers, the leading contribution to $\log \mathcal{I}$ reproduces the BH entropy function, with subleading corrections captured by the Cardy-like expansion. These results support a modular-like structure in 4d SUSY partition functions and provide a universal entropy function for holographic SCFTs in the Cardy-like regime.
Abstract
We show that the superconformal index of N=1 superconformal field theories in four dimensions has an asymptotic growth of states which is exponential in the charges. Our analysis holds in a Cardy-like limit of large charges, for which the index is dominated by small values of chemical potentials. In this limit we find the saddle points of the integral that defines the superconformal index using two different methods. One method, valid for finite N, is to first take the Cardy-like limit and then find the saddle points. The other method is to analyze the saddle points at large N and then take the Cardy-like limit. The result of both analyses is that the asymptotic growth of states of the superconformal index exactly agrees with the Bekenstein-Hawking entropy of supersymmetric black holes in the dual AdS$_5$ theory.
