N=2 Supersymmetric Black Attractors in Six and Seven Dimensions

TL;DR

This paper explores the structure of N=2 supersymmetric black attractors in six and seven dimensions, utilizing quaternionic geometry of the moduli space of type IIA string theory on K3 surfaces, and derives explicit formulas for potentials and prepotentials.

Contribution

It introduces a quaternionic formulation of the moduli space, constructs the special hyperKahler geometry, and explicitly derives the hyperKahler potential, prepotential, and flux potential for 6D black objects, extending to 7D.

Findings

Explicit hyperKahler potential involving V0 and S matrices

Holomorphic prepotential and flux potential derived from topology

Uplift to 7D resembles 4D/5D black hole correspondence

Abstract

Using a quaternionic formulation of the moduli space $\boldsymbol{M}({\small IIA/K3}) $ of 10D type IIA superstring on a generic K3 complex surface with volume $\boldsymbol{V}_{0}$, we study extremal $\mathcal{N}=2$ black attractors in 6D space-time and their uplifting to 7D. For the 6D theory, we exhibit the role played by 6D $\mathcal{N}=1$ hypermultiplets and the $Z^{m}$ central charges isotriplet of the 6D $\mathcal{N}=2$ superalgebra. We construct explicitly the special hyperKahler geometry of $% \boldsymbol{M}({\small IIA/K3}) $ and show that the $SO(4) \times SO(20) $ invariant hyperKahler potential is given by $\mathcal{H}=\mathcal{H}_{0}+\mathrm{Tr}[ \ln (1-% \boldsymbol{V}_{0}^{-1}\boldsymbol{S}) ] $ with Kahler leading term $\mathcal{H}_{0}=\mathrm{Tr}[ \ln \boldsymbol{V}_{0}] $ plus an extra term which can be expanded as a power series in $\boldsymbol{V}%_{0}^{-1}$ and the traceless and symmetric 3$\times $3 matrix $\boldsymbol{S} $. We also derive the holomorphic matrix prepotential $\mathcal{G}$ and the flux potential $\mathcal{G}_{BH}$ of the 6D black objects induced by the topology of the RR field strengths $\mathcal{F}_{2}=d\mathcal{A}_{1}$ and $% \mathcal{F}_{4}=d\mathcal{A}_{3}$ on the K3 surface and show that $\mathcal{G% }_{BH}$ reads as $Q_{0}+\sum_{m=1}^{3}q^{m}Z^{m}$. Moreover, we reveal that $% Z^{m}=\sum_{I=1}^{20}Q_{I}(\int_{C_{2}^{I}}J^{m}) $ where the isotriplet $J^{m}$ is the hyperKahler 2- form on the K3 surface. It is found as well that the uplifting to seven dimensions is quite similar to 4D/5D correspondence for back hole potential considered in arXiv 0707.0964 [hep-th].