Conformal matter in warped backgrounds

Warped backgrounds in five-dimensional models can provide solutions to various hierarchy problems in particle physics if the Standard Model matter is associated with the zero modes of bulk fields with non-trivial profiles along the extra dimension. We investigate the case of a conformally coupled massless scalar. This field possesses a zero mode whose action density is exponentially enhanced along the transverse direction in a warped background, i.e., near the negative tension brane in the RS setting. At the zero mode level effective 5D composites of this scalar and its derivatives, which are suppressed by powers of the fundamental gravitational scale, yield 4D interactions of electroweak strength. This suggests a certain importance of conformally coupled scalar fields for extra-dimensional model building.