Bulk Fields in Dilatonic and Self-Tuning Flat Domain Walls

We study the Kaluza-Klein zero modes of massless bulk fields with variousspins in the background of dilatonic and self-tuning flat domain walls. We findthat the zero modes of all the massless bulk fields in such domain wallbackgrounds are normalizable, unlike those in the background of thenon-dilatonic domain wall with infinite extra space of Randall and Sundrum. Inparticular, gravity in the bulk of dilatonic domain walls is effectivelycompactified to the Einstein gravity with vanishing cosmological constant andfinite gravitational constant in one lower dimensions for any values of dilatoncoupling parameter, provided the warp factor is chosen to decrease on bothsides of the domain wall, in which case the tension of the domain wall ispositive. However, unexpectedly, for the self-tuning flat domain walls, thecosmological constant of the effective gravity theory in one lower dimensionsdoes not vanish.