896 research outputs found
The 331 model with right-handed neutrinos
We explore some more consequences of the electroweak
model with right-handed neutrinos. By introducing the mixing angle
, the {\it exact} physical eigenstates for neutral gauge bosons are
obtained. Because of the mixing, there is a modification to the coupling
proportional to . The data from the -decay allows us to fix the
limit for as . >From the neutrino
neutral current scatterings, we estimate a bound for the new neutral gauge
boson mass in the range 300 GeV, and from symmetry-breaking hierarchy a
bound for the new charged and neutral (non-Hermitian) gauge bosons are obtained.Comment: Slight changes in section 5, Latex, 16 page
Radiatively Induced Neutrino Masses and Large Higgs-Neutrino Couplings in the Standard Model with Majorana Fields
The Higgs sector of the Standard Model with one right-handed neutrino per
family is systematically analyzed. In a model with intergenerational
independent mixings between families, we can account for very light neutrinos
acquiring Majorana masses radiatively at the first electroweak loop level. We
also find that in such a scenario the Higgs coupling to the light-heavy
neutrinos and to the heavy-heavy ones may be remarkably enhanced with
significant implications for the production of these heavy neutrinos at high
energy colliders.Comment: Making the text of an old paper electronically availabl
Exotic quark effects on the Higgs sector of the USSM at the LHC
The Higgs sector of the U(1)-extended supersymmetric model is studied with
great detail. We calculate the masses of the Higgs bosons at the one-loop
level. We also calculate at the one-loop level the gluon-involving processes
for the productions and decays of the scalar Higgs bosons of the model at the
energy of the CERN Large Hadron Collider (LHC), where the radiative corrections
due to the loops of top, bottom, and exotic quarks and their scalar partners
are taken into account. We find that the exotic quark and exotic scalar quarks
in the model may manifest themselves at the LHC, since the production of the
heaviest scalar Higgs boson via gluon fusion processes is mediated virtually by
the loops of exotic quark and exotic scalar quarks, for a reasonable parameter
set of the model.Comment: 36 pages, 13 figures, JP
Recent Developments in Precision Electroweak Physics
Developments in precision electroweak physics in the two years since the
symposium are briefly summarized.Comment: Update on recent developments, prepared for the publication of the
Proceedings of Alberto Sirlin Symposium, New York University, October 2000.
10 pages, 1 figur
Possible Candidates for SUSY SO(10) Model with an Intermediate Scale
We study the possibility of an intermediate scale existing in supersymmetric
SO(10) grand unified theories: The intermediate scale is demanded to be around
10^{12} GeV so that neutrinos can obtain masses suitable for explaining the
experimental data on the deficit of solar neutrino with
Mikheev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We
show that any Pati-Salam type intermediate symmetries are excluded by requiring
reasonable conditions and only is likely to be realized as an intermediate symmetry.Comment: LaTeX, 8 pages + 1 uuencoded eps figure (Error corrected
SU(3)_LxU(1)_N Model for Right-Handed Neutrino Neutral Currents
A model based on the \mbox{SU(3)}_L\otimes \mbox{U(1)}_N gauge group, in
which neutrinos have right-handed neutral currents is considered. We argue that
in order to have a result consistent with low-energy one, the right-handed
neutrino component must be treated as correction instead of an equivalent spin
state.Comment: 6 pages, Latex, no figures, Accepted for publication in Phys. Rev.
K_L \ra \mu^\pm e^\mp \nu \overline{\nu} as background to K_L \ra \mu^\pm e^\mp
We consider the process K_L \ra \mu^\pm e^\mp \nu \overline{\nu} at next to
leading order in chiral perturbation theory. This process occurs in the
standard model at second order in the weak interaction and constitutes a
potential background in searches for new physics through the modes K_L \ra
\mu^\pm e^\mp. We find that the same cut, ~MeV, used to remove
the sequential decays K_{l3}\ra \pi_{l2} pushes the B(K_L \ra \mu^\pm e^\mp
\nu \overline{\nu}) to the level, effectively removing it as a
background.Comment: 8 pages, LaTeX, 1 figure appended as postscript file after
\end{document}. Fermilab-Pub-93/024-
Forward-Backward Asymmetries in Hadronically Produced Lepton Pairs
It has now become possible to observe appreciable numbers of hadronically
produced lepton pairs in mass ranges where the contributions of the photon and
are comparable. Consequently, in the reaction , substantial forward-backward asymmetries can be seen. These
asymmetries provide a test of the electroweak theory in a new regime of
energies, and can serve as diagnostics for any new neutral vector bosons
coupling both to quarks and to charged lepton pairs.Comment: 11 pages, latex, 4 uuencoded figures sent separately, Fig. 2 revise
Nucleon mass and pion loops: Renormalization
Using Dyson--Schwinger equations, the nucleon propagator is analyzed
nonperturbatively in a field--theoretical model for the pion--nucleon
interaction. Infinities are circumvented by using pion--nucleon form factors
which define the physical scale. It is shown that the correct, finite,
on--shell nucleon renormalization is important for the value of the mass--shift
and the propagator. For physically acceptable forms of the pion--nucleon form
factor the rainbow approximation together with renormalization is inconsistent.
Going beyond the rainbow approximation, the full pion--nucleon vertex is
modelled by its bare part plus a one--loop correction including an effective
. It is found that a consistent value for the nucleon mass--shift can
be obtained as a consequence of a subtle interplay between wave function and
vertex renormalization. Furthermore, the bare and renormalized pion--nucleon
coupling constant are approximately equal, consistent with results from the
Cloudy Bag Model.Comment: 14 pages, 6 figure
Two-loop renormalization of gaugino masses in general supersymmetric gauge models
We calculate the two-loop renormalization group equations for the running
gaugino masses in general SUSY gauge models, improving our previous result. We
also study its consequence to the unification of the gaugino masses in the SUSY
SU(5) model. The two-loop correction to the one-loop relation
is found to be of the order of a few \%.Comment: 8 pages + 1 figure (omitted),KEK-TH-371 / UT-65
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