Non-compact AdS(5) universe with parallel positive tension 3-branes

We construct the general model with only parallel positive tension 3-branes on M-4 x R-1 and M-4 x R-1/Z(2). The cosmology constant is sectional const ant along the fifth dimension. In this general scenario, the 5-dimensional GUT scale on each brane can he indentified as the 5-dimensional Planck scal e, but, the 4-dimensional Planck scale is generated from the low 4-dimensio nal GUT scale exponentially in our world. We also give two simple models to show explicitly how to solve the gauge hierarchy problem. (C) 2000 Elsevie r Science B.V. All rights reserved.