c-extremization from toric geometry
Antonio Amariti, Luca Cassia, Silvia Penati
TL;DR
This work derives a geometric, toric-diagram-based formulation for the 2d central charge $c_r$ of $(0,2)$ SCFTs arising from the partial topological twist of 4d toric quiver theories on a curved Riemann surface. By identifying the 2d mixing parameters with toric perfect-matching charges and equating fluxes to PM data, the authors express $c_r$ in terms of triple-dacetroid determinants of the toric diagram and then extremize to obtain the exact 2d central charge. The framework is validated across a broad set of examples, including smooth and singular horizons (where perimeter-point handling is required) and demonstrates that baryonic symmetries can mix with the 2d R-current, mirroring but generalizing known 4d phenomena. The results deepen the connection between 2d c-extremization and 4d a-maximization, and suggest holographic links to volumes of internal manifolds, with several avenues for further exploration in AdS$_3$/CFT$_2$ holography and toric geometry techniques.
Abstract
We derive a geometric formulation of the 2d central charge $c_r$ from infinite families of 4d $\mathcal{N}=1$ superconformal field theories topologically twisted on constant curvature Riemann surfaces. They correspond to toric quiver gauge theories and are associated to D3 branes probing five dimensional Sasaki-Einstein geometries in the AdS/CFT correspondence. We show that $c_r$ can be expressed in terms of the areas of the toric diagram describing the moduli space of the 4d theory, both for toric geometries with smooth and singular horizons. We also study the relation between a-maximization in 4d and c-extremization in 2d, giving further evidences of the mixing of the baryonic symmetries with the exact R-current in two dimensions.
