629 research outputs found
Removing Ambiguities in the Neutrino Mass Matrix
We suggest that the weak-basis independent condition det(M_nu)=0 for the
effective neutrino mass matrix can be used in order to remove the ambiguities
in the reconstruction of the neutrino mass matrix from input data available
from present and future feasible experiments. In this framework, we study the
full reconstruction of M_nu with special emphasis on the correlation between
the Majorana CP-violating phase and the various mixing angles. The impact of
the recent KamLAND results on the effective neutrino mass parameter is also
briefly discussed.Comment: 11 pages, 4 figures. Comments and references added; final version to
appear in Phys. Lett.
Hidrogenionic potential (pH) of the attractant, trap density and control threshold for Ceratitis capitata (Diptera: tephritidae) on Hamlin oranges in São Paulo central region, Brazil
This study evaluated the effect of initial pH values of 4.5, 6.5 and 8.5 of the attractant
(protein bait) Milhocina® and borax (sodium borate) in the feld, on the capture of fruit flies in McPhail
traps, using 1, 2, 4 and 8 traps per hectare, in order to estimate control thresholds in a Hamlin orange grove
in the central region of the state of São Paulo. The most abundant fruit fly species was Ceratitis capitata,
comprising almost 99% of the fruit flies captured, of which 80% were females. The largest captures of C.
capitata were found in traps baited with Milhocina® and borax at pH 8.5. Captures per trap for the four
densities were similar, indicating that the population can be estimated with one trap per hectare in areas
with high populations. It was found positive relationships between captures of C. capitata and the number
of Hamlin oranges damaged, 2 and 3 weeks after capture. It was obtained equations that correlate captures
and damage levels which can be used to estimate control thresholds. The average loss caused in Hamlin
orange fruits by C. capitata was 2.5 tons per hectare or 7.5% of production.Esta pesquisa teve como objetivos: avaliar o efeito do pH inicial, 4.5; 6.5 e 8.5, do atrativo
proteico Milhocina® e bórax (tetraborato de sódio) na captura de moscas-das-frutas em armadilhas McPhail;
estudar densidades de armadilhas, 1; 2; 4 e 8 por hectare, para estimar níveis de controle em laranja cv.
Hamlin, na região central de São Paulo. A espécie predominante, com 99% das moscas-das-frutas capturadas,
foi Ceratitis capitata, sendo 80% de fêmeas. As maiores capturas de C. capitata ocorreram nas armadilhas
com Milhocina® e bórax em pH 8.5. As capturas, nas 4 densidades, foram semelhantes, indicando que a
população pode ser estimada com uma armadilha por hectare em áreas de altas populações. Houve relações
positivas entre capturas de C. capitata e o número de frutos danificados, 2 e 3 semanas após a captura. Assim,
foram obtidas equações que relacionam a captura e o dano, possibilitando estimar níveis de controle desse
inseto. As perdas médias causadas por C. capitata em laranja cv. Hamlin chegaram a 2,5 toneladas de frutos
por hectare ou 7,5% da produção.info:eu-repo/semantics/publishedVersio
Minimal Scenarios for Leptogenesis and CP Violation
The relation between leptogenesis and CP violation at low energies is
analyzed in detail in the framework of the minimal seesaw mechanism. Working,
without loss of generality, in a weak basis where both the charged lepton and
the right-handed Majorana mass matrices are diagonal and real, we consider a
convenient generic parametrization of the Dirac neutrino Yukawa coupling matrix
and identify the necessary condition which has to be satisfied in order to
establish a direct link between leptogenesis and CP violation at low energies.
In the context of the LMA solution of the solar neutrino problem, we present
minimal scenarios which allow for the full determination of the cosmological
baryon asymmetry and the strength of CP violation in neutrino oscillations.
Some specific realizations of these minimal scenarios are considered. The
question of the relative sign between the baryon asymmetry and CP violation at
low energies is also discussed.Comment: 36 pages, 5 figures; minor corrections and references updated. Final
version to appear in Phys. Rev.
Leptogenesis, CP violation and neutrino data: What can we learn?
A detailed analytic and numerical study of baryogenesis through leptogenesis
is performed in the framework of the standard model of electroweak interactions
extended by the addition of three right-handed neutrinos, leading to the seesaw
mechanism. We analyze the connection between GUT-motivated relations for the
quark and lepton mass matrices and the possibility of obtaining a viable
leptogenesis scenario. In particular, we analyze whether the constraints
imposed by SO(10) GUTs can be compatible with all the available solar,
atmospheric and reactor neutrino data and, simultaneously, be capable of
producing the required baryon asymmetry via the leptogenesis mechanism. It is
found that the Just-So^2 and SMA solar solutions lead to a viable leptogenesis
even for the simplest SO(10) GUT, while the LMA, LOW and VO solar solutions
would require a different hierarchy for the Dirac neutrino masses in order to
generate the observed baryon asymmetry. Some implications on CP violation at
low energies and on neutrinoless double beta decay are also considered.Comment: 36 pages, 6 figures; new references added, final version to appear in
Nucl. Phys.
-- Crisis and New Physics
The experimental values of and are the only data which do not
seem to agree with Standard Model predictions. Although it is still premature
to draw any definite conclusions, it is timely to look for new physics which
could explain the excess in and deficit in . We investigate this
problem in a simple extension of the Standard Model, where a charge
isosinglet quark is added to the standard spectrum. Upon the further
introduction of an extra scalar doublet, one finds a solution with interesting
consequences.Comment: 12 pages, REVTEX, no figure
Unified Topological Inference for Brain Networks in Temporal Lobe Epilepsy Using the Wasserstein Distance
Persistent homology can extract hidden topological signals present in brain
networks. Persistent homology summarizes the changes of topological structures
over multiple different scales called filtrations. Doing so detect hidden
topological signals that persist over multiple scales. However, a key obstacle
of applying persistent homology to brain network studies has always been the
lack of coherent statistical inference framework. To address this problem, we
present a unified topological inference framework based on the Wasserstein
distance. Our approach has no explicit models and distributional assumptions.
The inference is performed in a completely data driven fashion. The method is
applied to the resting-state functional magnetic resonance images (rs-fMRI) of
the temporal lobe epilepsy patients collected at two different sites:
University of Wisconsin-Madison and the Medical College of Wisconsin. However,
the topological method is robust to variations due to sex and acquisition, and
thus there is no need to account for sex and site as categorical nuisance
covariates. We are able to localize brain regions that contribute the most to
topological differences. We made MATLAB package available at
https://github.com/laplcebeltrami/dynamicTDA that was used to perform all the
analysis in this study
Fitting Neutrino Physics with a U(1)_R Lepton Number
We study neutrino physics in the context of a supersymmetric model where a
continuous R-symmetry is identified with the total Lepton Number and one
sneutrino can thus play the role of the down type Higgs. We show that
R-breaking effects communicated to the visible sector by Anomaly Mediation can
reproduce neutrino masses and mixing solely via radiative contributions,
without requiring any additional degree of freedom. In particular, a relatively
large reactor angle (as recently observed by the Daya Bay collaboration) can be
accommodated in ample regions of the parameter space. On the contrary, if the
R-breaking is communicated to the visible sector by gravitational effects at
the Planck scale, additional particles are necessary to accommodate neutrino
data.Comment: 19 pages, 3 figures; v2: references added, constraints updated,
overall conclusions unchange
Neutrino Masses and Lepton Flavour Violation in Thick Brane Scenarios
We address the issue of lepton flavour violation and neutrino masses in the
``fat-brane'' paradigm, where flavour changing processes are suppressed by
localising different fermion field wave-functions at different positions (in
the extra dimensions) in a thick brane. We study the consequences of
suppressing lepton number violating charged lepton decays within this scenario
for lepton masses and mixing angles. In particular, we find that charged lepton
mass matrices are constrained to be quasi-diagonal. We further consider whether
the same paradigm can be used to naturally explain small Dirac neutrino masses
by considering the existence of three right-handed neutrinos in the brane, and
discuss the requirements to obtain phenomenologically viable neutrino masses
and mixing angles. Finally, we examine models where neutrinos obtain a small
Majorana mass by breaking lepton number in a far away brane and show that, if
the fat-brane paradigm is the solution to the absence of lepton number
violating charged lepton decays, such models predict, in the absence of flavour
symmetries, that charged lepton flavour violation will be observed in the next
round of rare muon/tau decay experiments.Comment: 33 pages, 9 eps figure
Bi-large Neutrino Mixing and Mass of the Lightest Neutrino from Third Generation Dominance in a Democratic Approach
We show that both small mixing in the quark sector and large mixing in the
lepton sector can be obtained from a simple assumption of universality of
Yukawa couplings and the right-handed neutrino Majorana mass matrix in leading
order. We discuss conditions under which bi-large mixing in the lepton sector
is achieved with a minimal amount of fine-tuning requirements for possible
models. From knowledge of the solar and atmospheric mixing angles we determine
the allowed values of sin \theta_{13}. If embedded into grand unified theories,
the third generation Yukawa coupling unification is a generic feature while
masses of the first two generations of charged fermions depend on small
perturbations. In the neutrino sector, the heavier two neutrinos are model
dependent, while the mass of the lightest neutrino in this approach does not
depend on perturbations in the leading order. The right-handed neutrino mass
scale can be identified with the GUT scale in which case the mass of the
lightest neutrino is given as (m_{top}^2/M_{GUT}) sin^2 \theta_{23} sin^2
\theta_{12} in the limit sin \theta_{13} = 0. Discussing symmetries we make a
connection with hierarchical models and show that the basis independent
characteristic of this scenario is a strong dominance of the third generation
right-handed neutrino, M_1, M_2 < 10^{-4} M_3, M_3 = M_{GUT}.Comment: typos correcte
Neutrino Masses, Mixing and New Physics Effects
We introduce a parametrization of the effects of radiative corrections from
new physics on the charged lepton and neutrino mass matrices, studying how
several relevant quantities describing the pattern of neutrino masses and
mixing are affected by these corrections. We find that the ratio omega = sin
theta / tan theta_atm is remarkably stable, even when relatively large
corrections are added to the original mass matrices. It is also found that if
the lightest neutrino has a mass around 0.3 eV, the pattern of masses and
mixings is considerably more stable under perturbations than for a lighter or
heavier spectrum. We explore the consequences of perturbations on some flavor
relations given in the literature. In addition, for a quasi-degenerate neutrino
spectrum it is shown that: (i) starting from a bi-maximal mixing scenario, the
corrections to the mass matrices keep tan theta_atm very close to unity while
they can lower tan theta_sol to its measured value; (ii) beginning from a
scenario with a vanishing Dirac phase, corrections can induce a Dirac phase
large enough to yield CP violation observable in neutrino oscillations.Comment: 14 pages, 21 figures. Uses RevTeX4. Added several comments and
references. Final version to appear in PR
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