hep-ph/0203034
The Effective Lagrangian in the Randall-Sundrum Model and Electroweak Physics
Authors: Csaba Csaki, Joshua Erlich, John Terning
We consider the two-brane Randall-Sundrum (RS) model with bulk gauge fields.
We carefully match the bulk theory to a 4D low-energy effective Lagrangian.
In addition to the four-fermion operators induced by KK exchange we find that
large negative S and T parameters are induced in the effective theory. This is
a tree-level effect and is a consequence of the shapes of the W and Z wave
functions in the bulk. Such effects are generic in extra dimensional theories
where the standard model (SM) gauge bosons have non-uniform wave functions
along the extra dimension. The corrections to precision electroweak observables
in the RS model are mostly dominated by S. We fit the parameters of the RS
model to the experimental data and find somewhat stronger bounds than
previously obtained; however, the standard model bound on the Higgs mass from
precision measurements can only be slightly relaxed in this theory.