266 research outputs found
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
, where is a small coupling constant and , in the
case of the first fermionic generation, is the scale of the dynamical quark
mass ( MeV). For the third fermion generation is the value
of the dynamical techniquark mass ( 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
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