Some questions about Randall Sundrum model

[maani]

Hi, I have been studied the Randall Sundrum Model for a while (original paper: hep-ph/9905221), but I don't come forward with it. So far I understood:

In the RS model the four dimensional Minkowskian spacetime is expanded by a fifth dimension, which is compactified on an orbifold S1/Z2.
What is an orbifold? What is Z2? And why on orbifold?
On the fixed points of this orbifold are located two 3-branes: the UV Brane, where the gravitation reside, and the IR or TeV brane, which is our universe with all SM particles.They form the border of the extra dimension. Only the gravitation can propagate through the extra dimension. The extra dimension is curved, the metric is given by ds2=e-2kr\phig\mu\nudx\mudx\nu-r2d\phi2

The metric is non factorizable. What does it mean? And why is this important? The exponential factor is called warp factor and is responsible for the large hierarchy between Plank and weak scale.

Well this is so war. I guess I need something like "RS model for dummies". Can anybody recommend me some paper, where the model is simply explained?

Thanks a lot in advance!

[atyy]

Try Raman Sundrum's 'Extra Dimensions Lecture 3'
http://www.pha.jhu.edu/~sundrum/presentations.html

Or his TASI 2004 Lectures: To the Fifth Dimension and Back
http://arxiv.org/abs/hep-th/0508134

[maani]

Hi I found the answers I needed. For those who are interested in RS models or Extra Dimensions this is a very good introduction: http://arxiv.org/abs/hep-ph/0409309