Graviton oscillations in the two-brane world

TL;DR

This paper investigates the effective gravitational action in a two-brane Randall-Sundrum model, revealing a tower of gravitational wave modes and radion-induced oscillations that could be detectable by interferometers.

Contribution

It introduces a nonlocal effective action framework that explains the origin of gravitational wave mode mixing and oscillations in braneworld scenarios.

Findings

Identifies an infinite sequence of gravitational wave modes including massless and massive Kaluza-Klein modes.

Shows mode mixing depends on the extra dimension's modulus, leading to oscillations.

Suggests these oscillations could be observed with gravitational-wave detectors.

Abstract

We study the braneworld effective action in the two-brane Randall-Sundrum model. In the framework of this essentially-nonlocal action we reveal the origin of an infinite sequence of gravitational wave modes -- the usual massless one as well as the tower of Kaluza-Klein massive ones. Mixing of the modes, which parametrically depends on the background value of the modulus of the extra dimension, can be interpreted as radion-induced gravitational-wave oscillations, a classical analogue to meson and neutrino oscillations. We show that these oscillations arising in M-theory-inspired braneworld setups could lead to effects detectable by gravitational-wave interferometers.