Strings in plane-fronted gravitational waves

TL;DR

This paper demonstrates that Brinkmann's plane-fronted gravitational waves, known as pp-waves, can serve as exact string vacua across all orders of the sigma-model perturbation expansion, under certain conditions.

Contribution

It establishes that pp-waves are exact solutions in string theory at all perturbative orders, extending their significance in theoretical physics.

Findings

pp-waves provide exact string vacua

valid at all orders of sigma-model perturbation

under specific conditions

Abstract

Brinkmann's plane-fronted gravitational waves with parallel rays --~shortly pp-waves~-- are shown to provide, under suitable conditions, exact string vacua at all orders of the sigma-model perturbation expansion.