Non-Simply-Connected Symmetries in 6D SCFTs
Markus Dierigl, Paul-Konstantin Oehlmann, Fabian Ruehle
TL;DR
<3-5 sentence high-level summary>We classify 6d N=(1,0) SCFTs engineered via F-theory in the presence of Mordell-Weil torsion, which enforces a non-trivial global group structure by modding out center elements and restricting representations. The authors develop a torsion-aware framework for constructing tensor branches, starting from non-Higgsable clusters and SCMs, and analyze how these global constraints modify flavor and gauge groups, anomalies, and possible deformations. They connect these geometric realizations to heterotic and M-theory perspectives, interpreting torsion as discrete holonomy instantons and orbifold sectors, and they provide a comprehensive SCM zoo organized by torsion type with explicit tensor-branch data. The results offer a principled path to a global-classification of 6d SCFTs with non-simply-connected symmetries and have implications for compactifications and lower-dimensional duals.
Abstract
Six-dimensional N=(1,0) superconformal field theories can be engineered geometrically via F-theory on elliptically-fibered Calabi-Yau 3-folds. We include torsional sections in the geometry, which lead to a finite Mordell-Weil group. This allows us to identify the full non-Abelian group structure rather than just the algebra. The presence of torsion also modifies the center of the symmetry groups and the matter representations that can appear. This in turn affects the tensor branch of these theories. We analyze this change for a large class of superconformal theories with torsion and explicitly construct their tensor branches. Finally, we elaborate on the connection to the dual heterotic and M-theory description, in which our configurations are interpreted as generalizations of discrete holonomy instantons.
