314 research outputs found
Classification and Application of Triangular Quark Mass Matrices
The hierarchical structure in the quark masses and mixings allows its ten
physical parameters to be most conveniently encoded in mass matrices of the
upper triangular form. We classify these matrices in the hierarchical, minimal
parameter basis where the mismatch between the weak and mass eigenstates
involves only small mixing angles. Ten such pairs are obtained for the up and
down quarks. This analysis can be used to classify texture zeros of general
mass matrices. For hermitian mass matrices with five texture zeros, this method
yields immediately five pairs of textures with simple, analytic predictions for
the quark mixings. Comparison with data indicates that, of the five pairs,
three are disfavored, one is marginally acceptable, while the fifth fits well.Comment: 18 pages, ReVTe
Neutrino mixing in matter
Three-neutrino mixing in matter is studied through a set of evolution
equations which are based on a rephasing invariant parametrization. Making use
of the known properties of measured neutrino parameters, analytic, approximate,
solutions are obtained. Their accuracy is confirmed by comparison with
numerical integration of these equations. The results, when expressed in the
elements squared of the mixing matrix, exhibit striking patterns as the matter
density varies.Comment: Revised, 5 pages, 3 figures, references added
Solar Neutrinos with Three Flavor Mixings
The recent 71Ga solar neutrino observation is combined with the 37Cl and
Kamiokande-II observations in an analysis for neutrino masses and mixings. The
allowed parameter region is found for matter enhanced mixings among all three
neutrino flavors. Distortions of the solar neutrino spectrum unique to three
flavors are possible and may be observed in continuing and next generation
experiments.Comment: August 1992 (Revised) PURD-TH-92-
Renormalization of the neutrino mass matrix
The renormalization group equations for the general 2 by 2, complex, neutrino
mass matrix are shown to have exact, analytic solutions. Simple formulas are
given for the physical mixing angle, complex phase and mass ratio in terms of
their initial values and the energy scales. We also establish a (complex)
renormalization invariant relating these parameters. The qualitative features
of the physical parameters' renormalization are clearly illustrated in vector
field plots. In both the SM and MSSM, maximal mixing is a saddle point.Comment: 16 pages, 5 figure
Constraints on Three-Neutrino Mixing from Atmospheric and Reactor Data
Observations of atmospheric neutrinos are usually analyzed using the
simplifying approximation that either or
two-flavor mixing is relevant. Here we
instead consider the data using the simplifying approximation that only one
neutrino mass scale is relevant. This approximation is the minimal three-flavor
notation that includes the two relevant two-flavor approximations. The
constraints in the parameter space orthogonal to the usual, two-flavor analyses
are studied.Comment: 15 pages, preprint IUHET-26
Maximal Neutrino Mixing from an Attractive Infrared Fixed Point
In the Standard Model (and MSSM), renormalization effects on neutrino mixing
are generally very small and the attractive fixed points are at vanishing
neutrino mixing. However for multi-higgs extensions of the Standard Model,
renormalization effects on neutrino mixing can be large and nontrivial fixed
points are possible. Here we examine a simple two-higgs model. For two flavors,
maximal mixing is an attractive infrared fixed point. For three flavors, the
neutrino mass matrix evolves towards large off-diagonal elements at low
energies. The experimentally suggested bimaximal neutrino mixing pattern is one
possible attractive infrared fixed point.Comment: 16 page
The Oscillation Probability of GeV Solar Neutrinos of All Active Species
In this paper, I address the oscillation probability of O(GeV) neutrinos of
all active flavours produced inside the Sun and detected at the Earth. Flavours
other than electron-type neutrinos may be produced, for example, by the
annihilation of WIMPs which may be trapped inside the Sun. In the GeV energy
regime, matter effects are important both for the ``1-3'' system and the
``1-2'' system, and for different neutrino mass hierarchies. A numerical scan
of the multidimensional three-flavour parameter space is performed,
``inspired'' by the current experimental situation. One important result is
that, in the three-flavour oscillation case, P{alpha,beta} is different from
P{beta,alpha} for a significant portion of the parameter space, even if there
is no CP-violating phase in the MNS matrix. Furthermore, P{mu,mu} has a
significantly different behaviour from P{tau,tau}, which may affect
expectations for the number of events detected at large neutrino telescopes.Comment: 38 pages, 10 figure
Supernova neutrino oscillations: A simple analytical approach
Analyses of observable supernova neutrino oscillation effects require the
calculation of the electron (anti)neutrino survival probability P_ee along a
given supernova matter density profile. We propose a simple analytical
prescription for P_ee, based on a double-exponential form for the crossing
probability and on the concept of maximum violation of adiabaticity. In the
case of two-flavor transitions, the prescription is shown to reproduce
accurately, in the whole neutrino oscillation parameter space, the results of
exact numerical calculations for generic (realistic or power-law) profiles. The
analytical approach is then generalized to cover three-flavor transitions with
(direct or inverse) mass spectrum hierarchy, and to incorporate Earth matter
effects. Compact analytical expressions, explicitly showing the symmetry
properties of P_ee, are provided for practical calculations.Comment: 22 pages (RevTeX) + 5 figures (PostScript
Testing quark mass matrices with right-handed mixings
In the standard model, several forms of quark mass matrices which correspond
to the choice of weak bases lead to the same left-handed mixings ,
while the right-handed mixings are not observable quantities. Instead, in
a left-right extension of the standard model, such forms are ansatze and give
different right-handed mixings which are now observable quantities. We
partially select the reliable forms of quark mass matrices by means of
constraints on right-handed mixings in some left-right models, in particular on
. Hermitian matrices are easily excluded.Comment: 12 pages RevTex, no figures. Minor corrections. Comment on SO(10)
changed and one reference adde
Non-adiabatic level crossing in (non-) resonant neutrino oscillations
We study neutrino oscillations and the level-crossing probability
P_{LZ}=\exp(-\gamma_n\F_n\pi/2) in power-law like potential profiles
. After showing that the resonance point coincides only for a
linear profile with the point of maximal violation of adiabaticity, we point
out that the ``adiabaticity'' parameter can be calculated at an
arbitrary point if the correction function \F_n is rescaled appropriately. We
present a new representation for the level-crossing probability,
P_{LZ}=\exp(-\kappa_n\G_n), which allows a simple numerical evaluation of
in both the resonant and non-resonant cases and where \G_n contains
the full dependence of on the mixing angle . As an application
we consider the case important for oscillations of supernova neutrinos.Comment: 4 pages, revtex, 3 eps figure
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