arXiv.org > hep-ph > arXiv:hep-ph/0505001
Top and Bottom: a Brane of Their Own
Giacomo Cacciapaglia, Csaba Csaki, Christophe Grojean, Matthew
Reece, John Terning
(Submitted on 29 Apr 2005 (v1), last revised 21 Jun 2005 (this version, v2))
We consider extra dimensional
descriptions of models where there are two separate strongly
interacting sectors contributing to electroweak symmetry breaking
(``topcolor'' type models). In the extra dimensional picture there
would be two separate (anti-de Sitter) bulks meeting on the Planck
brane, with each bulk having its own corresponding IR (TeV) brane.
Sources for electroweak symmetry breaking can then be localized on
both of these IR branes, while the different generations of fermions
may be separated from each other. We describe the modes propagating
in such a setup, and consider the cases where the electroweak
symmetry breaking on either of the two IR branes come either from a
higgsless scenario (via boundary conditions) or a (top-)Higgs. We
show that the tension that exists between obtaining a large top
quark mass and the correct value of the Zb\bar{b} couplings in
ordinary higgsless models can be largely relieved in the
higgsless--top-Higgs versions of the two IR brane models. This may
also be true in the purely higgsless--higgsless case, however since
that model is necessarily in the strongly coupled regime the
tree-level results for the properties of the third generation may
get large corrections. A necessary consequence of such models is the
appearance of additional pseudo-Goldstone bosons (``top-pions''),
which would be strongly coupled to the third generation.