The moduli space of vacua of N=2 class S theories
Dan Xie, Kazuya Yonekura
TL;DR
The paper develops a geometric framework to describe the full moduli space of vacua for 4d ${\cal N}=2$ class ${\cal S}$ theories, including Coulomb, Higgs, and mixed branches, via generalized Hitchin equations arising from twisted compactifications of 5d maximal SYM. A central role is played by holomorphic factorization of the Seiberg-Witten curve and by boundary data at punctures encoded as (nilpotent) orbits, with regular and irregular singularities treated distinctly. The authors provide a concrete algorithm to identify mixed-branch roots and compute the dimensions of Coulomb and Higgs factors, applied to a broad set of theories: ${\cal N}=2$ SQCD, the $T_N$ theory, Maldacena-Nunez theories, and various Argyres-Douglas theories. The results reproduce known field-theoretic conclusions (e.g., SQCD branch structures and AD points) and offer a unified framework for non-Lagrangian theories, enabling systematic exploration of vacua across regular and irregular puncture data and their coupled 5d SYM extensions.
Abstract
We develop a systematic method to describe the moduli space of vacua of four dimensional $\mathcal{N}=2$ class ${\cal S}$ theories including Coulomb branch, Higgs branch and mixed branches. In particular, we determine the Higgs and mixed branch roots, and the dimensions of the Coulomb and Higgs components of mixed branches. They are derived by using generalized Hitchin's equations obtained from twisted compactification of 5d maximal Super-Yang-Mills, with local degrees of freedom at punctures given by (nilpotent) orbits. The crucial thing is the holomorphic factorization of the Seiberg-Witten curve and reduction of singularity at punctures. We illustrate our method by many examples including ${\mathcal N}=2$ SQCD, $T_N$ theory and Argyres-Douglas theories.
