Special Arithmetic of Flavor
Matteo Caorsi, Sergio Cecotti
TL;DR
The work reframes the rank-1 ${\cal N}=2$ SW landscape through Diophantine geometry by treating special geometries as elliptic surfaces over the chiral ring, using the Kodaira-Néron model to classify non-free theories via the pair $(\mathcal{E},F_\infty)$. It shows that SW completeness aligns with the safely irrelevant conjecture and that the flavor content is encoded in the Mordell-Weil lattice, with $E_8$-root curves yielding flavor roots through good-position integral/narrow sections; the Oguiso-Shioda tables then determine admissible flavor groups. The analysis connects discrete gaugings to base changes of elliptic surfaces, and provides a comprehensive, geometry-driven account that agrees with Argyres et al. across known rank-1 classifications. The framework unifies UV behavior, flavor symmetry, and deformation data into a coherent arithmetic picture, enabling systematic exploration of discrete gauging and flavor-root structures via rational elliptic surfaces and their Mordell-Weil lattices.
Abstract
We revisit the classification of rank-1 4d $\mathcal{N}=2$ QFTs in the spirit of Diophantine Geometry, viewing their special geometries as elliptic curves over the chiral ring (a Dedekind domain). The Kodaira-Néron model maps the space of non-trivial rank-1 special geometries to the well-known moduli of pairs $(\mathcal{E},F_\infty)$ where $\mathcal{E}$ is a relatively minimal, rational elliptic surface with section, and $F_\infty$ a fiber with additive reduction. Requiring enough Seiberg-Witten differentials yields a condition on $(\mathcal{E},F_\infty)$ equivalent to the "safely irrelevant conjecture". The Mordell-Weil group of $\mathcal{E}$ (with the Néron-Tate pairing) contains a canonical root system arising from $(-1)$-curves in special position in the Néron-Severi group. This canonical system is identified with the roots of the flavor group $\mathsf{F}$: the allowed flavor groups are then read from the Oguiso-Shioda table of Mordell-Weil groups. Discrete gaugings correspond to base changes. Our results are consistent with previous work by Argyres et al.
