171 research outputs found
Fitting Ranked English and Spanish Letter Frequency Distribution in U.S. and Mexican Presidential Speeches
The limited range in its abscissa of ranked letter frequency distributions
causes multiple functions to fit the observed distribution reasonably well. In
order to critically compare various functions, we apply the statistical model
selections on ten functions, using the texts of U.S. and Mexican presidential
speeches in the last 1-2 centuries. Dispite minor switching of ranking order of
certain letters during the temporal evolution for both datasets, the letter
usage is generally stable. The best fitting function, judged by either
least-square-error or by AIC/BIC model selection, is the Cocho/Beta function.
We also use a novel method to discover clusters of letters by their
observed-over-expected frequency ratios.Comment: 7 figure
Neutrino mass matrix with U(2) flavor symmetry and neutrino oscillations
The three neutrino mass matrices in the model are studied
focusing on the neutrino oscillation experiments. The atmospheric neutrino
anomaly could be explained by the large oscillation.
The long baseline experiments are expected to detect signatures of the neutrino
oscillation even if the atmospheric neutrino anomaly is not due to the neutrino
oscillation. However, the model cannot solve the solar neutrino deficit while
it could be reconciled with the LSND data.Comment: 12 pages, LaTex file, to be published in PR
Effects of neutrino oscillations and neutrino magnetic moments on elastic neutrino-electron scattering
We consider elastic antineutrino-electron scattering taking into account
possible effects of neutrino masses and mixing and of neutrino magnetic moments
and electric dipole moments. Having in mind antineutrinos produced in a nuclear
reactor we compute, in particular, the weak-electromagnetic interference terms
which are linear in the magnetic (electric dipole) moments and also in the
neutrino masses. We show that these terms are, however, suppressed compared to
the pure weak and electromagnetic cross section. We also comment upon the
possibility of using the electromagnetic cross section to investigate neutrino
oscillations.Comment: 12 pages, REVTEX file, no figures, submitted to Phys.Rev.
Is CP Violation Observable in Long Baseline Neutrino Oscillation Experiments ?
We have studied CP violation originated by the phase of the neutrino mixing
matrix in the long baseline neutrino oscillation experiments. The direct
measurements of CP violation is the difference of the transition probabilities
between CP-conjugate channels. In those experiments, the CP violating effect is
not suppressed if the highest neutrino mass scale is taken to be 1\sim 5 \eV,
which is appropriate for the cosmological hot dark matter. Assuming the
hierarchy for the neutrino masses, the upper bounds of CP violation have been
caluculated for three cases, in which mixings are constrained by the recent
short baseline ones. The calculated upper bounds are larger than ,
which will be observable in the long baseline accelerator experiments. The
matter effect, which is not CP invariant, has been also estimated in those
experiments.Comment: 28 pages, LaTex file, 6 figures included using epsfig Matter effect
is estimated(Figs.3(a) (b)). Physical parameters are change
Hierarchical Four-Neutrino Oscillations With a Decay Option
We present a new and novel synthesis of all existing neutrino data regarding
the disappearance and appearance of and . We assume four
neutrinos: , as well as a heavier singlet neutrino
of a few eV. The latter may decay into a massless Goldstone boson (the
singlet Majoron) and a linear combination of the doublet antineutrinos. We
comment on how this scenario may be verified or falsified in future
experiments.Comment: 13 pages, no figur
Progress in neutrino oscillation searches and their implications
Neutrino Oscillation, in which a given flavour of neutrino transforms into
another is a powerful tool for probing small neutrino masses. The intrinsic
neutrino properties involved are neutrino mass squared difference
and the mixing angle in vacuum . In this talk I will summarize the
progress that we have achieved in our search for neutrino oscillation with
special emphasis on the recent results from the Sudbury Neutrino Observatory
(SNO) on the measurement of solar neutrino fluxes. I will outline the current
bounds on the neutrino masses and mixing parameters and discuss the major
physics goals of future neutrino experiments in the context of the present
picture.Comment: Plenary Talk, WHEPP-7, January 2002, published in Pramana, Vol. 60,
261, 200
Muon-anti-neutrino <---> electron-anti-neutrino mixing: analysis of recent indications and implications for neutrino oscillation phenomenology
We reanalyze the recent data from the Liquid Scintillator Neutrino Detector
(LSND) experiment, that might indicate anti-nu_muanti-nu_e mixing. This
indication is not completely excluded by the negative results of established
accelerator and reactor neutrino oscillation searches. We quantify the region
of compatibility by means of a thorough statistical analysis of all the
available data, assuming both two-flavor and three-flavor neutrino
oscillations. The implications for various theoretical scenarios and for future
oscillation searches are studied. The relaxation of the LSND constraints under
different assumptions in the statistical analysis is also investigated.Comment: 17 pages (RevTeX) + 9 figures (Postscript) included with epsfig.st
Accelerator and Reactor Neutrino Oscillation Experiments in a Simple Three-Generation Framework
We present a new approach to the analysis of neutrino oscillation
experiments, in the one mass-scale limit of the three-generation scheme. In
this framework we reanalyze and recombine the most constraining accelerator and
reactor data, in order to draw precise bounds in the new parameter space. We
consider our graphical representations as particularly suited to show the
interplay among the different oscillation channels. Within the same framework,
the discovery potential of future short and long baseline experiments is also
investigated, in the light of both the recent signal from the LSND experiment
and the atmospheric neutrino anomaly.Comment: uuencoded compressed tar file. Figures (13) available by ftp to
ftp://eku.sns.ias.edu/pub/lisi/ (192.16.204.30). Submitted to Physical Review
Constraints on long-baseline neutrino oscillation probabilities and CP asymmetries from neutrino oscillation data
We consider long-baseline neutrino oscillations in the framework of two
schemes with mixing of four massive neutrinos which can accommodate all the
existing indications in favour of neutrino mixing. Within these schemes, we
derive bounds on the oscillation probabilities and the CP-odd
neutrino-antineutrino asymmetries in long-baseline experiments. Using the
results of short-baseline neutrino oscillation experiments, we obtain rather
strong upper bounds on the long-baseline probabilities 1-P(nu_e->nu_e) and
P(nu_mu->nu_e). Nevertheless, the projected sensitivities of the MINOS and
ICARUS experiments are better than our bounds. We also show that there are no
corresponding constraints for nu_mu->nu_mu and nu_mu->nu_tau long-baseline
oscillations and that the CP-odd asymmetry in the latter channel can reach the
maximal value allowed by the unitarity of the mixing matrix. Some schemes with
mixing of three neutrinos are also considered.Comment: 32 pages including 5 figures, RevTeX. New discussion of the matter
effect
Constraints on Exotic Mixing of Three Neutrinos
Exotic explanations are considered for atmospheric neutrino observations. Our
analysis includes matter effects and the mixing of all three neutrinos under
the simplifying assumption of only one relevant mixing scale. Constraints from
accelerator, reactor and solar neutrinos are included. We find that the
proposed mixing mechanisms based on violations of Lorentz invariance or on
violations of the equivalence principle cannot explain the recent observations
of atmospheric neutrino mixing. However the data still allow a wide range of
energy dependences for the vacuum mixing scale, and also allow large
electron-neutrino mixing of atmospheric neutrinos. Next generation long
baseline experiments will constrain these possibilities.Comment: 27 pages, 4 figure
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