Gravitational waves from WZW models

TL;DR

This paper reviews recent solutions of non-compact WZW models describing NS-supported pp-wave backgrounds, focusing on correlator computations, the Penrose limit as a contraction, and implications for holography and flat space limits.

Contribution

It introduces a method to compute correlators in non-compact WZW models and connects the Penrose limit to a contraction of U(1)xSU(2)_k models, aiding holography understanding.

Findings

Computed three and four-point correlators using current algebra techniques.

Demonstrated the Penrose limit as a contraction of WZW models.

Discussed the existence of two flat space limits.

Abstract

A brief review is given of the recent solution of a non-compact CFT describing a NS-supported pp-wave background. We will first explain how to compute the three and four-point correlators using current algebra techniques, thereby showing that some generic features of the non-compact WZW models become very clear in this simple context. We will then present the Penrose limit as a contraction of an U(1)xSU(2)_k WZW model, an approach that could prove useful in order to understand holography for pp-wave space-times. We will finally comment on the string amplitudes and on the existence of two flat space limits.