NS5 Brane and Little String Duality in the pp-wave Limit

TL;DR

This paper analyzes NSR strings in a specific background derived from NS5-branes, solving the spectrum in light-cone gauge, and explores its connection to little string theory, confirming expected duality relations.

Contribution

It provides an exact solution for the string spectrum in the Nappi-Witten background and links it to little string theory via duality considerations.

Findings

Spectrum is space-time supersymmetric.

Energy-angular momentum relationship matches flat background results.

Supports NS5-brane and little string duality in the pp-wave limit.

Abstract

We study NSR strings in the Nappi-Witten background, which is the Penrose limit of a certain NS5-brane supergravity solution. We solve the theory in the light-cone gauge, obtaining the spectrum, which is space-time supersymmetric. In light of the LST/NS5-brane duality, this spectrum should be in correspondence with the states of little string theory in the appropriate limit. A semiclassical analysis verifies that the relationship between energy and angular momentum, after a field redefinition, matches the known result for a flat background.