Classification of 5-Dimensional Space-Time with Parallel 3-Branes

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http://arabica.ecs.soton.ac.uk/examples/hep-th/9912182.pdf



MADPH-99-1150
Classification of 5-Dimensional Space-Time with
Parallel 3-Branes
Tianjun Li 1

Department of Physics, University of Wisconsin, Madison, WI 53706, U. S. A.
Abstract

If the fth dimension is one-dimensional connected manifold, up to di eo-
morphic, the only possible space-time will be M4 R1, M4 R1=Z2, M4 S1
and M4 S1=Z2. And there exist two possibilities on cosmology constant: the
cosmology constant is constant along the fth dimension, and the cosmology
constant is sectional constant along the fth dimension.
 
We construct the general models with parallel 3-branes on those kinds of the space-time and with constant/sectional constant cosmology constant, and point out that for compact fth dimension, the sum of the brane tensions is zero, for non-compact fth dimension, the sum of the brane tensions is positive. We assume the observable
brane which includes our world should have positive tension, and obtain that
in those general scenarios, the 5-dimensional GUT scale on each brane can be
identified as the 5-dimensional Planck scale, but, the 4-dimensional Planck
scale is generated from the low 4-dimensional GUT scale exponentially in our
world. We also give some simple models to show explicitly how to solve the
gauge hierarchy problem.

PACS: 11.25.Mj; 04.65.+e; 11.30.Pb; 12.60. Jv
Keywords: AdS5; Compactication; Brane; Scale; Hierarchy