Neutrino Masses in Theories with Dynamical Breaking of Electroweak and Extended Gauge Symmetries

We address the problem of accounting for light neutrino masses in theories with dynamical electroweak symmetry breaking. We discuss this in the context of a class of (extended) technicolor (ETC) models and analyze the full set of Dirac and Majorana masses that arise in such theories. As a possible solution, we propose a combination of suppressed Dirac masses and a seesaw involving dynamically generated condensates of standard-model singlet, ETC-nonsinglet fermions. We show how this can be realized in an explicit ETC model. An important feature of this proposal is that, because of the suppression of Dirac neutrino mass terms, a seesaw yielding realistic neutrino masses does not require superheavy Majorana masses; indeed, these Majorana masses are typically much smaller than the largest ETC scale. We then generalize this construction to theories with dynamical breaking of the left-right gauge group G_LR = SU(3)_c × SU(2)_L × SU(2)_R × U(1) _B-L and its extension to the Pati-Salam gauge group G₄₂₂ = SU(4)_PS × SU(2)_L × SU(2)_R.