Fermion mass splitting in the technicolor coupled scenario

Abstract

We discuss fermion mass generation in unified models where QCD and technicolor (or any two strongly interacting theories) have their Schwinger–Dyson equations coupled. In this case the technicolor (TC) and QCD self-energies are modified in comparison with the behavior observed in the isolated theories. In these models the pseudo-Goldstone boson masses are much higher than the ones obtained in different contexts, and phenomenological signals, except from a light scalar composite boson, will be quite difficult to be observed at present collider energies. The most noticeable fact of these models is how the mass splitting between the different ordinary fermions is generated. We discuss how a necessary horizontal (or family) symmetry can be implemented in order to generate the mass splitting between fermions of different generations; how the fermionic mass spectrum may be modified due to GUT interactions, as well as how the mass splitting within the same fermionic generation are generated due to electroweak and GUT interactions.

Limit on Higgs boson trilinear self-coupling in coupled technicolor models

“…(7) in models like the ones of Ref. [8,10]. 1) that modifies the running of the N technifermion self-energy, wich turn out to be logarithmic due to the coupling to the QCD self-energy.…”

“…the mass hierarchy between different ordinary fermionic generations can only be obtained through the introduction of a family (or horizontal) symmetry, as described in Refs. [7,9,10]. We will not touch these aspects here, and in the following we just verify consequences of Eq.…”

“…This result can already constrain the dynamics of a composite Higgs boson in the context of coupled technicolor models [7][8][9][10], and can also be used to determine limits on the possible masses of pseudo-Goldstone bosons.…”

“…A consequence of a self-energy like the one of Eq. ( 11) is that TC coupled models must incorporate a family symmetry, in such a way that technifermions couple at leading order only to the third ordinary fermion family, whereas the first fermionic family will be coupled at leading order only to QCD [7,9,10], i.e. the mass hierarchy between different ordinary fermionic generations can only be obtained through the introduction of a family (or horizontal) symmetry, as described in Refs.…”

“…(7), in models like the ones of Ref. [8,10], corresponds to the ETC correction for m N due to the quark b, however, it can be disregarded since m b << µ tc . The third diagram of Fig.…”