364 research outputs found
Dynamics of chiral oscillations - A comparative analysis with spin-flipping
Chiral oscillation as well as spin flipping effects correspond to quantum
phenomena of fundamental importance in the context of particle physics and, in
particular, of neutrino physics. From the point of view of first quantized
theories, we are specifically interested in appointing the differences between
chirality and helicity by obtaining their dynamic equations for a fermionic
Dirac-type particle (neutrino). We also identify both effects when the
non-minimal coupling with an external (electro)magnetic field in the neutrino
interacting Lagrangian is taken into account. We demonstrate that, however,
there is no constraint between chiral oscillations, when it takes place in
vacuum, and the process of spin flipping related to the helicity quantum
number, which does not take place in vacuum. To conclude, we show that the
origin of chiral oscillations (in vacuum) can be interpreted as position very
rapid oscillation projections onto the longitudinal direction of momentum.Comment: 14 pages, no figure
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
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
Neutrino oscillations and neutrinoless double beta decay
The relation between neutrino oscillation parameters and neutrinoless double
beta decay is studied, assuming normal and inverse hierarchies for Majorana
neutrino masses. For normal hierarchy the crucial dependence on U_{e3} is
explored. The link with tritium beta decay is also briefly discussed.Comment: RevTex, 9 pages with 3 figures. Few comments and references adde
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
Reconstructing Seesaws
We explore some aspects of "reconstructing" the heavy singlet sector of
supersymmetric type I seesaw models, for two, three or four singlets. We work
in the limit where one light neutrino is massless. In an ideal world, where
selected coefficients of the TeV-scale effective Lagrangian could be measured
with arbitrary accuracy, the two-singlet case can be reconstructed, two three
or more singlets can be differentiated, and an inverse seesaw with four
singlets can be reconstructed. In a more realistic world, we estimate \ell_\a
\to \ell_\b \gamma expectations with a "Minimal-Flavour-Violation-like"
ansatz, which gives a relation between ratios of the three branching ratios.
The two singlet model predicts a discrete set of ratios.Comment: 14 page
NDVI da canola obtido com sensor Green Seeker e calculado a partir de dados hiperespectrais.
Orientador: Genei Antonio Dalmago
Relation between CPT Violation in Neutrino masses and mixings
The neutrino parameters determined from the solar neutrino data and the
anti-neutrino parameters determined from KamLAND reactor experiment are in good
agreement with each other. However, the best fit points of the two sets differ
from each other by about eV in mass-square differenc and by about
in the mixing angle. Future solar neutrino and reactor anti-neutrino
experiments are likely to reduce the uncertainties in these measurements. This,
in turn, can lead to a signal for CPT violation in terms a non-zero difference
between neutrino and anti-neutrino parameters. In this paper, we propose a CPT
violating mass matrix which can give rise to the above differences in both
mass-squared difference and mixing angle and study the constraints imposed by
the data on the parameters of the mass matrix.Comment: 10page
CP Violation in Bilarge Lepton Mixing
We propose a scheme of lepton mixing in which the unitary matrix that
diagonalizes the neutrino mass matrix is bimaximal and the deviation from
bimaximal of the lepton mixing matrix is due to the unitary matrix that
diagonalizes the charged-lepton mass matrix. This matrix is assumed to be
hierarchical, like the quark mixing matrix. It is shown that in general it is
possible to have a sizable value for |U_{e3}| together with an effective
two-neutrino maximal mixing in solar neutrino experiments. If the effective
mixing in solar neutrino experiments is less than maximal, as indicated by
current data, |U_{e3}| is bounded from below. Furthermore, in general the
violation of CP could be relatively large.Comment: 11 pages. Final version to be published in PR
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