Topcolor model in extra dimensions and nontrivial boundary conditions
  The nontrivial boundary conditions for the Topcolor breaking are investigated in the context of the TeV-scale extra dimension scenario. We present a six dimensional model where the top and bottom quarks in the bulk have the Topcolor charge while the other quarks in the bulk do not. We also put the electroweak gauge interaction in the six dimensional bulk. Then the bottom quark condensation is naturally suppressed owing to the power-like running of the bulk $U(1)_Y$ interaction, so that only the top condensation is expected to take place. We explore such a possibility based on the ladder Schwinger-Dyson equation and show the cutoff to make the model viable. 
Michio Hashimoto