Supersymmetric Kaluza-Klein reductions of M-waves and MKK-monopoles

TL;DR

This paper classifies supersymmetric Kaluza-Klein reductions of M-theory backgrounds, revealing new IIA configurations involving branes and monopoles, and discusses geometric features like moduli spaces and flux branes.

Contribution

It provides a comprehensive classification of smooth supersymmetric reductions of M-theory backgrounds, introducing new configurations and analyzing geometric properties such as moduli space structure.

Findings

Discovery of new supersymmetric IIA configurations with branes and monopoles

Identification of reductions with no continuous moduli

Proposal of an interpretation for flux 5-branes as bound states

Abstract

We investigate the Kaluza-Klein reductions to ten dimensions of the purely gravitational half-BPS M-theory backgrounds: the M-wave and the Kaluza-Klein monopole. We determine the moduli space of smooth (supersymmetric) Kaluza-Klein reductions by classifying the freely-acting spacelike Killing vectors which preserve some Killing spinor. As a consequence we find a wealth of new supersymmetric IIA configurations involving composite and/or bound-state configurations of waves, D0 and D6-branes, Kaluza-Klein monopoles in type IIA and flux/nullbranes, and some other new configurations. Some new features raised by the geometry of the Taub-NUT space are discussed, namely the existence of reductions with no continuous moduli. We also propose an interpretation of the flux 5-brane in terms of the local description (close to the branes) of a bound state of D6-branes and ten-dimensional Kaluza-Klein monopoles.