Gravitational waves in warped compactifications

TL;DR

This paper investigates how warping in extra dimensions affects the spectrum of gravitational waves, providing explicit formulas and numerical insights into the lowered Kaluza-Klein masses.

Contribution

It offers a complete explicit expression for the warp factor and Green's function on a torus, and analyzes the impact of warping on gravitational wave spectra in string compactifications.

Findings

Warp factor modifies the Kaluza-Klein spectrum.

First masses of gravitational waves are lowered due to warping.

Spectrum deviates from standard toroidal models.

Abstract

We study gravitational waves propagating on a warped Minkowski space-time with D-4 compact extra dimensions. While Kaluza-Klein scales are typically too high for any current detection, we analyse how the warp factor changes the Kaluza-Klein spectrum of gravitational waves. To that end we provide a complete and explicit expression for the warp factor, as well as the Green's function, on a d-dimensional torus. This expression differs from that of braneworld models and should find further uses in string compactifications. We then evaluate the Kaluza-Klein spectrum of gravitational waves. Our preliminary numerical results indicate not only a deviation from the standard toroidal spectrum, but also that the first masses get lowered due to the warp factor.