677 research outputs found
Bi-large neutrino mixing and the Cabibbo angle
Recent measurements of the neutrino mixing angles cast doubt on the validity
of the so-far popular tri-bimaximal mixing ansatz. We propose a parametrization
for the neutrino mixing matrix where the reactor angle seeds the large solar
and atmospheric mixing angles, equal to each other in first approximation. We
suggest such bi-large mixing pattern as a model building standard, realized
when the leading order value of the reactor angle equals the Cabibbo angle.Comment: 4 pages, 2 figs. v2: matches version appearing in Phys.Rev.D, rapid
communication
Unknowns after the SNO Charged-Current Measurement
We perform a model-independent analysis of solar neutrino flux rates
including the recent charged-current measurement at the Sudbury Neutrino
Observatory (SNO). We derive a universal sum rule involving SNO and
SuperKamiokande rates, and show that the SNO neutral-current measurement can
not fix the fraction of solar oscillating to sterile neutrinos. The
large uncertainty in the SSM B flux impedes a determination of the sterile
neutrino fraction.Comment: Version to appear in PRL; includes analysis with anticipated SNO NC
measuremen
On the Evolution of the Neutrino State inside the Sun
We reexamine the conventional physical description of the neutrino evolution
inside the Sun. We point out that the traditional resonance condition has
physical meaning only in the limit of small values of the neutrino mixing
angle, theta<<1. For large values of theta, the resonance condition specifies
neither the point of the maximal violation of adiabaticity in the nonadiabatic
case, nor the point where the flavor conversion occurs at the maximal rate in
the adiabatic case. The corresponding correct conditions, valid for all values
of theta including theta>pi/4, are presented. An adiabaticity condition valid
for all values of theta is also described. The results of accurate numerical
computations of the level jumping probability in the Sun are presented. These
calculations cover a wide range of Delta m^2, from the vacuum oscillation
region to the region where the standard exponential approximation is good. A
convenient empirical parametrization of these results in terms of elementary
functions is given. The matter effects in the so-called "quasi-vacuum
oscillation regime" are discussed. Finally, it is shown how the known
analytical results for the exponential, 1/x, and linear matter distributions
can be simply obtained from the formula for the hyperbolic tangent profile. An
explicit formula for the jumping probability for the distribution N_e ~
(coth(x/l) +- 1) is obtained.Comment: 34 pages, 8 figure
Search for exotic contributions to atmospheric neutrino oscillations
The energy spectrum of neutrino-induced upward-going muons in MACRO was
analysed in terms of relativity principles violating effects, keeping standard
mass-induced atmospheric neutrino oscillations as the dominant effect. The data
disfavor these possibilities even at a sub-dominant level; stringent 90% C.L.
limits are placed on the Lorentz invariance violation parameter at = 0 and at = 1. The limits can be re-interpreted as
bounds on the Equivalence Principle violation parameters.Comment: Presented at the 29th I.C.R.C., Pune, India (2005
New interactions: past and future experiments
In this talk I will review the present status and future perspectives of some
popular extensions of the conventional three-neutrino oscillation scenario,
from a purely phenomenological point of view. For concreteness I will focus
only on three specific scenarios: non-standard neutrino interactions with
matters, models with extra sterile neutrinos, and neutrino decay and
decoherence.Comment: LaTeX file using jpconf class, 8 pages, 2 tables. Proceedings of the
"XXIII International Conference on Neutrino Physics and Astrophysics"
(Neutrino 08), Christchurch, New Zealand, May 25-31, 200
Statistical Analysis of future Neutrino Mass Experiments including Neutrino-less Double Beta Decay
We perform a statistical analysis with the prospective results of future
experiments on neutrino-less double beta decay, direct searches for neutrino
mass (KATRIN) and cosmological observations. Realistic errors are used and the
nuclear matrix element uncertainty for neutrino-less double beta decay is also
taken into account. Three benchmark scenarios are introduced, corresponding to
quasi-degenerate, inverse hierarchical neutrinos, and an intermediate case. We
investigate to what extend these scenarios can be reconstructed. Furthermore,
we check the compatibility of the scenarios with the claimed evidence of
neutrino-less double beta decay.Comment: Matches published version: Europhys.Lett.85:51002 (2009). Format
changed suitably for ArXi
Dynamical solution to the problem at TeV scale
We introduce a new confining force (\mu-color) at TeV scale to dynamically
generate a supersymmetry preserving mass scale which would replace the \mu
parameter in the minimal supersymmetric standard model (MSSM). We discuss the
Higgs phenomenology and also the pattern of soft supersymmetry breaking
parameters allowing the correct electroweak symmetry breaking within the
\mu-color model, which have quite distinctive features from the MSSM and also
from other generalizations of the MSSM.Comment: 12 pages, REVte
Charged Lepton Electric Dipole Moments from TeV Scale Right-handed Neutrinos
We study the connection between charged lepton electric dipole moments,
, and seesaw neutrino mass generation in a simple two Higgs
doublet extension of the Standard Model plus three right-handed neutrinos (RHN)
, . For RHN with hierarchical masses and at least one with mass
in the 10 TeV range we obtain the upper bounds of
e-cm and e-cm. Our scenario favors the normal
mass hierarchy for the light neutrinos. We also calculated the cross section
for e^-e^- \ra W^- W^- in a high luminosity collider with constraints from
neutrinoless double beta decay of nuclei included. Among the rare muon decay
experiments we find that \mu\ra e\gamma is most sensitive and the upper limit
is .Comment: references added, typos correcte
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