Symmetry structure of special geometries
B. de Wit, F. Vanderseypen, A. Van Proeyen
TL;DR
The article analyzes how the isometry algebras of special geometries—real, Kähler, and quaternionic—are shaped by dimensional reduction via the r-map and c-map, revealing systematic enhancements and hidden symmetries. It develops a detailed, algebraic framework for the symmetry structure, including root-lattice decompositions, solvable subalgebras, and Iwasawa decompositions, and applies this to both generic and homogeneous spaces. A central outcome is that homogeneous d-spaces can be fully characterized as coset spaces G/H, with explicit constructions based on Clifford algebras and cubic data d_{ABC}, and with symmetry content that distinguishes symmetric from non-symmetric cases. These results illuminate how higher-dimensional origins constrain lower-dimensional moduli spaces and duality groups, advancing understanding of dualities and geometric structures in N=2 supergravity and string compactifications.
Abstract
Using techniques from supergravity and dimensional reduction, we study the full isometry algebra of Kähler and quaternionic manifolds with special geometry. These two varieties are related by the so-called c-map, which can be understood from dimensional reduction of supergravity theories or by changing chirality assignments in the underlying superstring theory. An important subclass, studied in detail, consists of the spaces that follow from real special spaces using the so-called r-map. We generally clarify the presence of `extra' symmetries emerging from dimensional reduction and give the conditions for the existence of `hidden' symmetries. These symmetries play a major role in our analysis. We specify the structure of the homogeneous special manifolds as coset spaces $G/H$. These include all homogeneous quaternionic spaces.
