Hypercharge-universal topcolor

We propose and discuss the phenomenology of a topcolor-assisted technicolor model with a flavor-universal hypercharge sector. After discussing the symmetry-breaking pattern and low-energy effective Lagrangian, we examine various experimental and theoretical constraints, finding that precision electroweak measurements yield the strongest bounds on the model. We perform a combined fit to all available Z-pole and LEP2 data and find that the goodness of fit for hypercharge-universal topcolor is comparable to that of the standard model. In contrast, topcolor-assisted technicolor models with a flavor nonuniversal hypercharge sector are markedly disfavored by the data.