4d N=2 Gauge Theories and Quivers: the Non-Simply Laced Case
Sergio Cecotti, Michele Del Zotto
TL;DR
The paper addresses constructing BPS quivers with superpotentials for 4d ${\cal N}=2$ theories with non-simply laced groups ${B_n},{C_n},{F_4},{G_2}$. It develops a geometric and categorical framework based on twisted (monodromic) fibrations and folding, introducing a specialization mechanism to incorporate matter representations and to generate new quiver theories. A central outcome is explicit quivers ${Q(\mathfrak{g})}$ with superpotentials ${\cal W(\mathfrak{g})}$ for BCFOG SYM, together with a detailed description of the light category $\mathscr{L}(\mathfrak{g})$, its monodromy, and how auxiliary fields render the construction tractable. The work also presents a versatile set of tools—monodromy, preprojective algebras for valued graphs, and specialization—that enable systematic generation of quivers for non-simply laced theories and their coupling to matter, with broader implications for geometric engineering and the BPS spectrum.
Abstract
We construct the BPS quivers with superpotential for the 4d N=2 gauge theories with non-simply laced Lie groups (B_n, C_n, F_4 and G_2). The construction is inspired by the BIKMSV geometric engineering of these gauge groups as non-split singular elliptic fibrations. From the categorical viewpoint of arXiv:1203.6743, the fibration of the light category L(g) over the (degenerate) Gaiotto curve has a monodromy given by the action of the outer automorphism of the corresponding unfolded Lie algebra. In view of the Katz--Vafa `matter from geometry' mechanism, the monodromic idea may be extended to the construction of (Q, W) for SYM coupled to higher matter representations. This is done through a construction we call specialization.
