Deciphering the minimum of energy of some walking technicolor models

There are quasi-conformal theories, like the Minimal and Ultraminimal Technicolor models, which may break dynamically the gauge symmetry of the Standard Model and at the same time are compatible with electroweak precision data. The main characteristic of this type of models is their fermionic content in one or more higher dimensional representations, therefore it is not immediate to know which model leads to the most attractive channel or the minimum vacuum energy state. We discuss the effective potential for composite operators for these models, verifying that their vacuum energy values are different, with the Ultraminimal model having a deeper minimum of energy.Comment: 4 pages, 2 figures, published version

Scalar bosons in Minimal and Ultraminimal Technicolor: Masses, trilinear couplings and widths

We compute masses, trilinear self-couplings and decay widths into weak bosons of the scalar composite bosons in the case of the Minimal and Ultraminimal technicolor models. The masses, computed via the Bethe-Salpeter equation, turn out to be light and the trilinear couplings smaller than the one that would be expected when compared to a fundamental Standard Model scalar boson with the same mass. The decay widths into electroweak bosons of the Ultraminimal model scalars bosons are much smaller than the one of the Minimal model.Comment: 15 pages, 1 figure, improved discussion, new references and typos corrected, matchs version to be publishe

A dynamical mechanism to explain the top-bottom quark mass hierarchy

We discuss the mass splitting between the the top and bottom quarks in a technicolor scenario. The model proposed here contains a left-right electroweak gauge group. An extended technicolor group and mirror fermions are introduced. The top-bottom quark mass splitting turns out to be intimately connected to the breaking of the left-right gauge symmetry. Weak isospin violation occurs within the experimental limits.Comment: Changes are made in sections I, II and IV; an new figure added; results unchanged; accepted for publication in Int. J. Mod. Phys.

Energy criterion to select the behavior of dynamical masses in technicolor models

We propose a quite general ansatz for the dynamical mass in technicolor models. We impose on this ansatz the condition for formation of the tightest composite boson state, or the criterion that it should lead to the deepest minimum of energy. This criterion indicates a particular form of the technifermion self energy.Comment: 4 pages, 3 figures; to appear in Phys. Lett.

Schwinger-Dyson equation boundary conditions induced by ETC radiative corrections

The technicolor (TC) Schwinger-Dyson equations (SDE) should include radiative corrections induced by extended technicolor (ETC) interactions when TC is embedded into a larger theory including also QCD. These radiative corrections couple the different strongly interacting Dyson equations. We discuss how the boundary conditions of the coupled SDE system are modified by these corrections, and verify that the ultraviolet behavior of the self-energies are described by a function that decreases logarithmically with momentum.Comment: 15 pages, 2 figure

The origin of the first and third generation fermion masses in a technicolor scenario

We argue that the masses of the first and third fermionic generations, which are respectively of the order of a few MeV up to a hundred GeV, are originated in a dynamical symmetry breaking mechanism leading to masses of the order $\alpha \mu$, where $\alpha$ is a small coupling constant and $\mu$, in the case of the first fermionic generation, is the scale of the dynamical quark mass ($\approx 250$ MeV). For the third fermion generation $\mu$ is the value of the dynamical techniquark mass ($\approx 250$ GeV). We discuss how this possibility can be implemented in a technicolor scenario, and how the mass of the intermediate generation is generated.Comment: 10 pages, 9 figures as eps files, Latex; Abridged version of the previous preprint. Title changed. Results remain the sam