Scalar propagator in the pp-wave geometry obtained from AdS_5 X S^5

TL;DR

This paper calculates scalar field propagators in a pp-wave background, revealing how massless and massive cases behave differently, with implications for understanding wave propagation in curved spacetime.

Contribution

It provides explicit formulas for scalar propagators in pp-wave geometry, connecting massive propagators to flat spacetime results and analyzing null geodesic confinement.

Findings

Massless propagator remains confined to null geodesics.

Massive propagator relates simply to flat spacetime propagator.

Retarded propagator exhibits null geodesic confinement.

Abstract

We compute the propagator for massless and massive scalar fields in the metric of the pp-wave. The retarded propagator for the massless field is found to stay confined to the surface formed by null geodesics. The algebraic form of the massive propagator is found to be related in a simple way to the form of the propagator in flat spacetime.