Superstring Gravitational Wave Backgrounds with Spacetime Supersymmetry

TL;DR

This paper investigates string theory-based gravitational wave backgrounds, determining their spectra and supersymmetry properties, with implications for understanding quantum gravity and string cosmology.

Contribution

It provides an exact analysis of a stringy gravitational wave background with spacetime supersymmetry, including spectrum, vacuum energy, and algebraic structure.

Findings

The background has N=4 supersymmetry in type II string theory.

The spectrum and vacuum energy are exactly determined.

The algebra is mapped to free bosons and fermions.

Abstract

We analyse the stringy gravitational wave background based on the current algebra $E^{c}_{2}$. We determine its exact spectrum and construct the modular invariant vacuum energy. The corresponding N=1 extension is also constructed. The algebra is again mapped to free bosons and fermions and we show that this background has N=4 (N=2) unbroken spacetime supersymmetry in the type II (heterotic case).