Unitary matrix models and random partitions: Universality and multi-criticality

TL;DR

This paper investigates multi-critical unitary matrix models using integrable operator formalism, revealing universal behaviors and phase structures, with applications to supersymmetric gauge theory indices in the large N limit.

Contribution

It introduces a universal framework for multi-critical unitary matrix models, extending Tracy--Widom distribution, and explores their phase structure and applications to gauge theories.

Findings

Universal results for multi-critical models in different coupling phases

Explicit computation of instanton sector free energy in weak coupling

Genus expansion of free energy in strong coupling

Abstract

The generating functions for the gauge theory observables are often represented in terms of the unitary matrix integrals. In this work, the perturbative and non-perturbative aspects of the generic multi-critical unitary matrix models are studied by adopting the integrable operator formalism, and the multi-critical generalization of the Tracy--Widom distribution in the context of random partitions. We obtain the universal results for the multi-critical model in the weak and strong coupling phases. The free energy of the instanton sector in the weak coupling regime, and the genus expansion of the free energy in the strong coupling regime are explicitly computed and the universal multi-critical phase structure of the model is explored. Finally, we apply our results in concrete examples of supersymmetric indices of gauge theories in the large $N$ limit.