Classification of IIB backgrounds with 28 supersymmetries

TL;DR

This paper classifies IIB supergravity backgrounds with 28 supersymmetries, showing they are all locally isometric to a specific plane wave solution and analyzing string propagation in this background.

Contribution

It proves that all IIB backgrounds with exactly 28 supersymmetries are locally isometric to a known plane wave solution and explores string dynamics within this background.

Findings

All 28-supersymmetry backgrounds are locally isometric to a specific plane wave.

Solutions with >26 supersymmetries and 5-form flux are maximally supersymmetric.

String spectrum and light-cone Hamiltonian are derived for the plane wave background.

Abstract

We show that all IIB backgrounds with strictly 28 supersymmetries are locally isometric to the plane wave solution of arXiv:hep-th/0206195. Moreover, we demonstrate that all solutions with more than 26 supersymmetries and only 5-form flux are maximally supersymmetric. The N=28 plane wave solution is a superposition of the maximally supersymmetric IIB plane wave with a heterotic string solution. We investigate the propagation of strings in this background, find the spectrum and give the string light-cone Hamiltonian.