  The dynamics of a stabilized radion in the Randall-Sundrum model (RS) with
two branes is investigated, and the effects of the radion on electroweak
precision observables are evaluated. The radius is assumed to be stabilized
using a bulk scalar field as suggested by Goldberger and Wise. First the mass
and the wavefunction of the radion is determined including the backreaction of
the bulk stabilization field on the metric, giving a typical radion mass of
order the weak scale. This is demonstrated by a perturbative computation of the
radion wavefunction. A consequence of the background configuration for the
scalar field is that after including the backreaction the Kaluza-Klein (KK)
states of the bulk scalars couple directly to the Standard Model fields on the
TeV brane. Some cosmological implications are discussed, and in particular it
is found that the shift in the radion at late times is in agreement with the
four-dimensional effective theory result. The effect of the radion on the
oblique parameters is evaluated using an effective theory approach. In the
absence of a curvature-scalar Higgs mixing operator, these corrections are
small and give a negative contribution to S. In the presence of such a mixing
operator, however, the corrections can be sizable due to the modified Higgs and
radion couplings.
