17,394 research outputs found
Inclusion of Z->b b-bar vertex corrections in Precision Electroweak Tests on the Sp(6)_L X U(1)_Y Model
We extend our previous work on the precision electroweak tests in the Sp(6)_L
X U(1)_Y family model to include for the first time the important Z->b b-bar
vertex corrections encoded in a new variable epsilon_b, utilizing all the
latest LEP data. We include in our analysis the one loop EW radiative
corrections due to the new bosons in terms of epsilon_1, epsilon_b and
. We find that the correlation between epsilon_1 and epsilon_b
makes the combined constraint much stronger than the individual ones. The model
is consistent with the recent CDF result of m_t=174\pm 10^{+13}_{-12}\GeV,
but it can not accomodate m_t\gsim 195\GeV.Comment: Latex, 16 pages+4 figures(not included but available as uuencoded or
PS files from [email protected]), PURD-TH-94-08, SNUTP-94-4
Precision Electroweak Tests on the Model
We perform precision electroweak tests on the model.
The purpose of the analysis is to delineate the model parameters such as the
mixing angles of the extra gauge bosons present in this model. We find that the
model is already constrained considerably by the present LEP data.Comment: 14 pages+2 figures(not included), PURD-TH-93-13, to appear in Phys.
Rev. D(figures available upon request by regular mail
Flavor Mixing and the Permutation Symmetry among Generations
In the standard model, the permutation symmetry among the three generations
of fundamental fermions is usually regarded to be broken by the Higgs
couplings. It is found that the symmetry is restored if we include the mass
matrix parameters as physical variables which transform appropriately under the
symmetry operation. Known relations between these variables, such as the
renormalization group equations, as well as formulas for neutrino oscillations
(in vacuum and in matter), are shown to be covariant tensor equations under the
permutation symmetry group.Comment: 12 page
Rephasing invariance and neutrino mixing
A rephasing invariant parametrization is introduced for three flavor neutrino
mixing. For neutrino propagation in matter, these parameters are shown to obey
evolution equations as functions of the induced neutrino mass. These equations
are found to preserve (approximately) some characteristic features of the
mixing matrix, resulting in solutions which exhibit striking patterns as the
induced mass varies. The approximate solutions are compared to numerical
integrations and found to be quite accurate.Comment: 18 pages, 6 figure
Renormalization of the Neutrino Mass Matrix
In terms of a rephasing invariant parametrization, the set of renormalization
group equations (RGE) for Dirac neutrino parameters can be cast in a compact
and simple form. These equations exhibit manifest symmetry under flavor
permutations. We obtain both exact and approximate RGE invariants, in addition
to some approximate solutions and examples of numerical solutions.Comment: 15 pages, 1figur
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