1,254 research outputs found
Softly Broken A_4 Symmetry for Nearly Degenerate Neutrino Masses
The leptonic Higgs doublet model of neutrino masses is implemented with an
A_4 discrete symmetry (the even permutation of 4 objects or equivalently the
symmetry of the tetrahedron) which has 4 irreducible representations: 1, 1',
1'', and 3. The resulting spontaneous and soft breaking of A_4 provides a
realistic model of charged-lepton masses as well as a nearly degenerate
neutrino mass matrix. Phenomenological consequences at and below the TeV scale
are discussed.Comment: 11 pages, no figur
Optical Alignment System for the PHENIX Muon Tracking Chambers
A micron-precision optical alignment system (OASys) for the PHENIX muon
tracking chambers is developed. To ensure the required mass resolution of
vector meson detection, the relative alignment between three tracking station
chambers must be monitored with a precision of 25m. The OASys is a
straightness monitoring system comprised of a light source, lens and CCD
camera, used for determining the initial placement as well as for monitoring
the time dependent movement of the chambers on a micron scale.Comment: Accepted for the publication in Nucl.Instr.Meth.
The \tau -> \mu \bar{\nu_i} \nu_i decay in the Randall Sundrum background with localized U(1)_Y gauge boson
We study the effects of localization of the U(1)_Y gauge boson around the
visible brane and the contributions of the KK modes of Z bosons on the BR of
the LFV \tau -> \mu \bar{\nu_i} \nu_i decay. We observe that the BR is
sensitive to the amount of localization of Z boson in the bulk of the Randall
Sundrum background.Comment: 13 pages, 4 figures,1 tabl
New "Square Root" Model of Lepton Family Cyclic Symmetry
Following the newly formulated notion of form invariance of the neutrino mass
matrix, a complete model of leptons is constructed. It is based on a specific
unitary 3 X 3 matrix U in family space, such that U^2 is the simple discrete
symmetry nu_e to -nu_e, nu_mu to nu_tau. Thus U also generates the cyclic group
Z_4. The charged-lepton mass matrix is nearly diagonal while the neutrino mass
matrix is of the form suitable for explaining maximal (large) mixing in
atmospheric (solar) neutrino oscillations in the context of three nearly
degenerate neutrino masses. Observable lepton flavor violation is predicted.
Quarks may be treated in the same way as the charged leptons.Comment: 10 pages, no figur
Supersymmetric Model of Muon Anomalous Magnetic Moment and Neutrino Masses
We propose the novel lepton-number relationship , which
is uniquely realized by the interaction in supersymmetry and may account for a possibly large
muon anomalous magnetic moment. Neutrino masses (with bimaximal mixing) may be
generated from the spontaneous and soft breaking of this lepton symmetry.Comment: 10 pages, including 2 figure
Nearly Bi-Maximal Neutrino Mixing, Muon g-2 Anomaly and Lepton-Flavor-Violating Processes
We interpret the newly observed muon g-2 anomaly in the framework of a
leptonic Higgs doublet model with nearly degenerate neutrino masses and nearly
bi-maximal neutrino mixing. Useful constraints are obtained on the rates of
lepton-flavor-violating rare decays ,
and as well as the - conversion ratio .
We find that , and
depend crucially on possible non-zero but samll values of the
neutrino mixing matrix element , and they are also sensitive to the
Dirac-type CP-violating phase. In particular, we show that , and are approximately in the ratio if is much larger than , and in the
ratio if is much lower than , where and are the corresponding mass-squared
differences of atmospheric and solar neutrino oscillations.Comment: LaTex 6 pages (2 PS figures). Phys. Rev. D (in printing
Lepton flavor violating signals of a little Higgs model at the high energy linear colliders
Littlest Higgs model predicts the existence of the doubly charged
scalars , which generally have large flavor changing couplings
to leptons. We calculate the contributions of to the lepton
flavor violating processes and , and compare our numerical results with the current
experimental upper limits on these processes. We find that some of these
processes can give severe constraints on the coupling constant and the
mass parameter . Taking into account the constraints on these free
parameters, we further discuss the possible lepton flavor violating signals of
at the high energy linear collider
experiments. Our numerical results show that the possible signals of
might be detected via the subprocesses in the future experiments.Comment: 16 pages, 7 figures. Discussions and references added, typos
correcte
TeV-scale seesaw from a multi-Higgs model
We suggest new simple model of generating tiny neutrino masses through a
TeV-scale seesaw mechanism without requiring tiny Yukawa couplings. This model
is a simple extension of the standard model by introducing extra one Higgs
singlet, and one Higgs doublet with a tiny vacuum expectation value.
Experimental constraints, electroweak precision data and no large flavor
changing neutral currents, are satisfied since the extra doublet only has a
Yukawa interaction with lepton doublets and right-handed neutrinos, and their
masses are heavy of order a TeV-scale. Since active light neutrinos are
Majorana particles, this model predicts a neutrinoless double beta decay.Comment: 21 pages, 8 figure
Slepton Oscillation at Large Hadron Collider
Measurement of Lepton-Flavor Violation (LFV) in the minimal SUSY Standard
Model (MSSM) at Large Hadron Collider (LHC) is studied based on a realistic
simulation. We consider the LFV decay of the second-lightest neutralino,
, in the case
where the flavor mixing exists in the right-handed sleptons. We scan the
parameter space of the minimal supergravity model (MSUGRA) and a more generic
model in which we take the Higgsino mass as a free parameter. We find
that the possibility of observing LFV at LHC is higher if is smaller than
the MSUGRA prediction; the LFV search at LHC can cover the parameter range
where the decay can be suppressed by the cancellation among
the diagrams for this case.Comment: 29 pages, 10 figure
Flavon exchange effects in models with abelian flavor symmetry
In models with abelian flavor symmetry the small mixing angles and mass
ratios of quarks and leptons are typically given by powers of small parameters
characterizing the spontaneous breaking of flavor symmetry by "flavon" fields.
If the scale of the breaking of flavor symmetry is near the weak scale, flavon
exchange can lead to interesting flavor-violating and CP violating effects.
These are studied. It is found that d_e, mu -> e + gamma, and mu-e conversion
on nuclei can be near present limits. For significant range of parameters mu-e
conversion can be the most sensitive way to look for such effects.Comment: 19 pages, 5 Postscript figures, LATE
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