Radion-induced gravitational wave oscillations and their phenomenology

Abstract

We discuss the theory and phenomenology of the interplay between the massless graviton and its massive Kaluza-Klein modes in the Randall-Sundrum two-brane model. The equations of motion of the transverse traceless degrees of freedom are derived by means of a Green function approach as well as from an effective nonlocal action. The second procedure clarifies the extraction of the particle content from the nonlocal action and the issue of its diagonalization. The situation discussed is generic for the treatment of two-brane models if the on-brane fields are used as the dynamical degrees of freedom. The mixing of the effective graviton modes of the localized action can be interpreted as radion-induced gravitational-wave oscillations, a classical analogy to meson and neutrino oscillations. We show that these oscillations arising in M-theorymotivated braneworld setups could lead to effects detectable by gravitational-wave interferometers. The implications of this effect for models with ultra-light gravitons are discussed.

Astrophysical consequences of extended cosmology

“…This is characteristic of most 5D theories, and exists for both induced-matter theory (Mashhoon et al 1998) and membrane theory (Youm 2000). It also exists for other higher-dimensional theories, though its form depends on the nature of the line element (Barvinsky et al 2002;Mukohyama 2003;Maartens 2003;Dahia et al 2003;Bertolami & Paramos 2004;Belayev 2004;Bini et al 2004). That such an extra force must exist in principle when the world is extended from 4D to 5D can be most quickly appreciated when we consider metric-based theories like those of Einstein for gravity and Maxwell for electromagnetism.…”

“…The new class of models is characterized by an irremoveable cosmological "constant", which may however decay with time and whose size agrees with astrophysical data (Lineweaver 1998;Overduin & Cooperstock 1998;Overduin 1999). The models are also characterized by an intrinsic extra force, which is the signature in 4D spacetime of 5D laws of dynamics (Mashhoon et al 1998;Wesson 1999;Youm 2000Youm , 2001Barvinsky et al 2002;Mukohyama 2003;Maartens 2003;Dahia et al 2003;Bertolami & Paramos 2004;Belayev 2004;Bini et al 2004). This so-called fifth force is common to both the current versions of 5D gravity, namely membrane and induced-matter theory, and will form the basis for much of the discussion below.…”

Graviton oscillations in the two-brane world

“…), i = 0, up to some nontrivial normalization coefficients. The details of this formalism will be presented in [6].…”

“…100 is a numerical coefficient depending on the trajectory and shape of the string loop, and ω is the characteristic frequency of string oscillations [16]. Thus the large gaugino vev can lead to the production of strong-amplitude GW's on the hidden brane, easily compensating the damping factor (25) [6].…”