Asymptotic growth of the 4d $\mathcal N=4$ index and partially deconfined phases

TL;DR

This paper investigates the asymptotic behavior of the 4d N=4 superconformal index, revealing partially deconfined phases, novel solutions to Bethe ansatz equations, and conjectures on the index's leading growth in the large-N limit.

Contribution

It introduces the concept of partially deconfined phases in the 4d N=4 index and uncovers new solutions to elliptic Bethe ansatz equations, providing a deeper understanding of the index's asymptotics.

Findings

Identification of partially deconfined phases with intermediate growth rates.

Discovery of new non-standard solutions to elliptic Bethe ansatz equations.

Conjecture on the leading asymptotics of the index in the large-N limit.

Abstract

We study the Cardy-like asymptotics of the 4d $\mathcal N=4$ index and demonstrate the existence of partially deconfined phases where the asymptotic growth of the index is not as rapid as in the fully deconfined case. We then take the large-$N$ limit after the Cardy-like limit and make a conjecture for the leading asymptotics of the index. While the Cardy-like behavior is derived using the integral representation of the index, we demonstrate how the same results can be obtained using the Bethe ansatz type approach as well. In doing so, we discover new non-standard solutions to the elliptic Bethe ansatz equations including continuous families of solutions for $SU(N)$ theory with $N\ge3$. We argue that the existence of both standard and continuous non-standard solutions has a natural interpretation in terms of vacua of $\mathcal N=1^*$ theory on $\mathbb R^3\times S^1$.