548 research outputs found
GUTs and String-GUTs
We look for a connection between string theories and Grand Unified Theories
(GUTs), with the aim to look for new insights in the existing four dimensional
string-GUT problems. We argue that the construction of consistent string-GUT
models could require the use of non canonical affine levels. We list the most
common level values related to realistic GUTs.Comment: 8 pages, Latex file, no figures. Acepted for publication in
Europhysics Letter
Systematic Study of 3-3-1 Models
We carry a systematic study of possible models based on the local gauge group
SU(3)_c X SU(3)_L X U(1)_X. Old and new models emerge from the analysis.Comment: 9 pages, Latex. Talk given at the VIII Mexican Workshop on Particles
and Fields, Zacatecas, Mexico, Nov. 14-20, 2001. To appear in the AIP
Proceeding
Mass Scales and Stability of the Proton in [SU(6)]Z
We proof that the proton is stable in the left-right symmetric gauge model
[SU(6)]Z, which unifies nongravitational forces with flavors,
broken spontaneously by a minimal set of Higgs Fields and Vacuum Expectation
Values down to SU(3)U(1)\hspace{0.2cm} . We also compute
the evolution of the gauge coupling constants and show how agreement with
precision data can be obtained.Comment: 14 page
Is U(1) a Good Family Symmetry?
We analyze U(1) as a horizontal symmetry and its possibilities to explain
the known elementary-fermion masses. We find that only two candidates, in the
context of SU(3)SU(2)U(1)U(1)
nonsupersymmetric, are able to fit the experimental result mm.Comment: 10 pages, Accepted for publication in Z. Phys.
FCNC in the 3-3-1 model with right-handed neutrinos
Flavor changing neutral currents coming from a new non-universal neutral
Gauge-Boson and from the non-unitary quark mixing matrix for the
model with right handed neutrinos are
studied. By imposing as experimental constraints the measured values of the 3x3
quark mixing matrix, the neutral meson mixing, and the bounds measured values
for direct flavor changing neutral current processes, the largest mixing of the
known quarks with the exotic ones can be established, with new sources of
flavor changing neutral currents being identified. Our main result is that for
a value smaller than one, large rates of rare top decays such as
, , and (where g stands for the gluon field)
are obtained; but if the model can survive present
experimental limits only if the mass of the new neutral Gauge Boson becomes
larger that 10 TeV.Comment: 30 pages, 1 figure. Accepted for publication in Phys. Rev.
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