Fermion masses and mixing in extended technicolor models

Thomas Appelquist, Maurizio Piai, Robert Shrock
2004 Physical Review D  
We study fermion masses and mixing angles, including the generation of a seesaw mechanism for the neutrinos, in extended technicolor (ETC) theories. We formulate an approach to these problems that relies on assigning right-handed Q=-1/3 quarks and charged leptons to ETC representations that are conjugates of those of the corresponding left-handed fermions. This leads to a natural suppression of these masses relative to the Q=2/3 quarks, as well as the generation of quark mixing angles, both
more » ... -standing challenges for ETC theories. Standard-model-singlet neutrinos are assigned to ETC representations that provide a similar suppression of neutrino Dirac masses, as well as the possibility of a realistic seesaw mechanism with no mass scale above the highest ETC scale of roughly 10^3 TeV. A simple model based on the ETC group SU(5) is constructed and analyzed. This model leads to non-trivial, but not realistic mixing angles in the quark and lepton sectors. It can also produce sufficiently light neutrinos, although not simultaneously with a realistic quark spectrum. We discuss several aspects of the phenomenology of this class of models.
doi:10.1103/physrevd.69.015002 fatcat:oqv7hzunvfdsfgikxbnrvnks64