Randall-Sundrum scenario with an extra warped dimension - art. no. 064003

We investigate a scenario with two four branes embedded in six dimensions. When the metric is periodic and compact in one of the dimensions parallel t o the branes, the value of the effective cosmological constant for the rema ining five dimensions can assume a variety of values, determined by the dep endence of the metric on the sixth dimension. The picture that emerges rese mbles the Randall-Sundrum model but with an extra warped dimension that all ows the usual brane-bulk fine tuning to be satisfied without finely tuning any of the parameters in the underlying six-dimensional theory. Although th e action contains terms with four derivatives of the metric, we show that w hen the branes have a finite, natural thickness, such terms have only a sma ll effect on the Randall-Sundrum structure. The presence of these four deri vative terms also allows a configuration that resembles that produced by a domain wall but which results from gravity alone.