296 research outputs found
Constraining the absolute neutrino mass scale and Majorana CP violating phases by future neutrinoless double beta decay experiments
Assuming that neutrinos are Majorana particles, in a three generation
framework, current and future neutrino oscillation experiments can determine
six out of the nine parameters which fully describe the structure of the
neutrino mass matrix. We try to clarify the interplay among the remaining
parameters, the absolute neutrino mass scale and two CP violating Majorana
phases, and how they can be accessed by future neutrinoless double beta
() decay experiments, for the normal as well as for the
inverted order of the neutrino mass spectrum. Assuming the oscillation
parameters to be in the range presently allowed by atmospheric, solar, reactor
and accelerator neutrino experiments, we quantitatively estimate the bounds on
, the lightest neutrino mass, that can be infered if the next generation
decay experiments can probe the effective Majorana mass
() down to
1 meV. In this context we conclude that in the case neutrinos are
Majorana particles: (a) if m_0 \gsim 300 meV, {\em i.e.}, within the range
directly attainable by future laboratory experiments as well as astrophysical
observations, then m_{ee} \gsim 30 meV must be observed;
(b) if meV, results from future decay
experiments combined with stringent bounds on the neutrino oscillation
parameters, specially the solar ones, will place much stronger limits on the
allowed values of than these direct experiments.Comment: 26 pages, 11 encapsulated postscript figures. A new figure and minor
changes are included. To be published in Phys. Rev.
Neutrino Mass Matrix Textures: A Data-driven Approach
We analyze the neutrino mass matrix entries and their correlations in a
probabilistic fashion, constructing probability distribution functions using
the latest results from neutrino oscillation fits. Two cases are considered:
the standard three neutrino scenario as well as the inclusion of a new sterile
neutrino that potentially explains the reactor and gallium anomalies. We
discuss the current limits and future perspectives on the mass matrix elements
that can be useful for model building.Comment: 25 pages, 18 figure
What can we learn about the lepton CP phase in the next 10 years?
We discuss how the lepton CP phase can be constrained by accelerator and
reactor measurements in an era without dedicated experiments for CP violation
search. To characterize globally the sensitivity to the CP phase \delta_{CP},
we introduce a new measure, the CP exclusion fraction, which quantifies what
fraction of the \delta_{CP} space can be excluded at a given input values of
\theta_{23} and \delta_{CP}. Using the measure we study the CP sensitivity
which may be possessed by the accelerator experiments T2K and NOvA. We show
that, if the mass hierarchy is known, T2K and NOvA alone may exclude,
respectively, about 50%-60% and 40%-50% of the \delta_{CP} space at 90% CL by
10 years running, provided that a considerable fraction of beam time is devoted
to the antineutrino run. The synergy between T2K and NOvA is remarkable,
leading to the determination of the mass hierarchy through CP sensitivity at
the same CL.Comment: Analyses and plots improved, conclusions unchanged, 23 pages, 8
figures, 1 tabl
CP Violation in Vacuum Neutrino Oscillation Experiments
We discuss the use of the CP asymmetry parameter (Acp) as a possible observable of CP violation in the leptonic sector. In order to do this, we study for a wide range of values of L/E the behavior of this asymmetry for the corresponding maximal value of the CP violation factor allowed by all present experimental limits on neutrino oscillations in vacuum and the recent Super-Kamiokande atmospheric neutrino result. We work in the three neutrino flavor framework
Three Generation Long-wavelength Vacuum Oscillation Solution to the Solar Neutrino Problem
We investigate the current status of the long-wavelength vacuum oscillation
solution to the solar neutrino problem and to what extent the presence of a
third neutrino can affect and modify it. Assuming that the smaller mass squared
difference that can induce such oscillations, , is in the
range eV and the larger one, , in the
range relevant to atmospheric neutrino observations, we analyze the most recent
solar neutrino data coming from Homestake, SAGE, GALLEX, GNO and
Super-Kamiokande experiments in the context of three neutrino generations. We
include in our vacuum oscillation analysis the MSW effect in the Sun, which is
relevant for some of the parameter space scrutinized. We have also performed,
as an extreme exercise, the fit without Homestake data. % While we found that
the MSW effect basically does not affect the best fitted parameters, it
significantly modifies the allowed parameter space for larger
than eV, in good agreement with the result
obtained by A. Friedland in the case of two generations. % Although the
presence of a third neutrino does not essentially improve the quality of the
fit, the solar neutrino data alone can give an upper bound on ,
which is constrained to be less than at 95 % C.L.Comment: 35 pages, 14 png figures: good quality postscript figures can be
found in http://neutrinos.if.usp.br/gefan/papers/publicados/ps/GNZ
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