Signatures of extra dimensions in gravitational waves

Abstract

Considering gravitational waves propagating on the most general 4+N-dimensional space-time, we investigate the effects due to the N extra dimensions on the four-dimensional waves. All wave equations are derived in general and discussed. On Minkowski4 times an arbitrary Ricci-flat compact manifold, we find: a massless wave with an additional polarization, the breathing mode, and extra waves with high frequencies fixed by Kaluza-Klein masses. We discuss whether these two effects could be observed.

Comments: v1: 21 pages + appendices, comments welcome! v2: few minor additions; v3: minor mistake corrected in the warped case, no impact on the main results, appendix A.2 modified