226 research outputs found
Implications of CHOOZ results for the decoupling of solar and atmospheric neutrino oscillations
We have considered the results of solar and atmospheric neutrino oscillation
experiments in the scheme of mixing of three neutrinos with a mass hierarchy.
It is shown that the recent results of the CHOOZ experiment imply that
|U_{e3}|^2<<1 (U is the neutrino mixing matrix), that the oscillations of solar
neutrinos are described by the two-generation formalism and that the
oscillations of solar and atmospheric neutrinos decouple. It is also shown that
if not only |U_{e3}|^2<<1 but also |U_{e3}|<<1, then the oscillations of
atmospheric neutrinos do not depend on matter effects and are described by the
two-generation formalism. In this case, with an appropriate identification of
the mixing parameters, the two-generation analyses of solar and atmospheric
neutrino data provide direct information on the mixing parameters of three
neutrinos. We discuss the possibility to get information on |U_{e3}|^2 in
long-baseline neutrino oscillation experiments.Comment: 12 pages, no figure
Possible tests for sterile neutrinos
It is shown that the future SNO and Super-Kamiokande experiments, in which
high energy neutrinos will be detected through the observation
of CC, NC and -- elastic scattering processes, could allow to reveal in
a model independent way the presence of sterile neutrinos in the flux of solar
neutrinos on the earth.Comment: Latex file, 6 pages including 1 figure. The postscript file of text
and figures is available at http://www.to.infn.it/teorici/giunti/papers.html
or ftp://ftp.to.infn.it/pub/giunti/1995/dftt-84-95/dftt-84-95.p
Neutrino Mixing and Future Solar Neutrino Experiments
Possibilities of a model independent treatment of the data from future
real-time solar neutrino experiments (SNO, Super-Kamiokande and others) are
discussed. It is shown that in the general case of transitions of the initial
solar 's into and/or the total flux of initial 8B
neutrinos and the survival probability can be determined directly from
the experimental data. Lower bounds for the probability of transition of solar
's into all possible sterile states are derived and expressed through
measurable quantities.Comment: 3 pages. Compressed postscript file. If you prefer the uncompressed
postscript file or a hardcopy of the paper, please write to
[email protected]. Talk presented by S.M. Bilenky at TAUP93. DFTT 66/9
Bruno Pontecorvo and modern neutrino physics
In this review, dedicated to the centenary of the birth of the great neutrino physicists Bruno Pontecorvo, I am discussing proposed by him radiochemical method of neutrino detection, his idea of the μ-e universality of the weak interaction and proposal of the accelerator neutrino experiment which allowed to proof that νe and νμ are different particles. In some details I discuss Pontecorvo’s pioneer idea of neutrino masses, mixing and oscillations and the development of this idea by Pontecorvo and Gribov and Pontecorvo and myself
Bruno Pontecorvo — pioneer of neutrino oscillations
In this brief review, dedicated to the centenary of the birth of the great neutrino physicist Bruno Pontecorvo, I am discussing his major contribution to neutrino physics, mainly to the physics of neutrino oscillations
Neutrinoless double-beta decay with three or four neutrino mixing
Considering the scheme with mixing of three neutrinos and a mass hierarchy
that can accommodate the results of solar and atmospheric neutrino experiments,
it is shown that the results of solar neutrino experiments imply a lower bound
for the effective Majorana mass in neutrinoless double-beta decay, under the
natural assumptions that massive neutrinos are Majorana particles and there are
no unlikely fine-tuned cancellations among the contributions of the different
neutrino masses. Considering the four-neutrino schemes that can accommodate
also the results of the LSND experiment, it is shown that only one of them is
compatible with the results of neutrinoless double-beta decay experiments and
with the measurement of the abundances of primordial elements produced in
Big-Bang Nucleosynthesis. It is shown that in this scheme, under the
assumptions that massive neutrinos are Majorana particles and there are no
cancellations among the contributions of the different neutrino masses, the
results of the LSND experiment imply a lower bound for the effective Majorana
mass in neutrinoless double-beta decay.Comment: 18 pages including 2 figures, RevTe
Mossbauer neutrinos in quantum mechanics and quantum field theory
We demonstrate the correspondence between quantum mechanical and quantum
field theoretical descriptions of Mossbauer neutrino oscillations. First, we
compute the combined rate of Mossbauer neutrino emission, propagation,
and detection in quantum field theory, treating the neutrino as an internal
line of a tree level Feynman diagram. We include explicitly the effect of
homogeneous line broadening due to fluctuating electromagnetic fields in the
source and detector crystals and show that the resulting formula for
is identical to the one obtained previously (Akhmedov et al., arXiv:0802.2513)
for the case of inhomogeneous line broadening. We then proceed to a quantum
mechanical treatment of Mossbauer neutrinos and show that the oscillation,
coherence, and resonance terms from the field theoretical result can be
reproduced if the neutrino is described as a superposition of Lorentz-shaped
wave packet with appropriately chosen energies and widths. On the other hand,
the emission rate and the detection cross section, including localization and
Lamb-Mossbauer terms, cannot be predicted in quantum mechanics and have to be
put in by hand.Comment: LaTeX, 16 pages, 1 figure; v2: typos corrected; matches published
versio
Constraints on long-baseline neutrino oscillations from the results of neutrino oscillation experiments
It is shown that in the two schemes with four massive neutrinos which are
compatible with the results of all neutrino oscillation experiments, the
probabilities of nu_e disappearance and nu_mu->nu_e appearance in long-baseline
experiments are severely constrained.Comment: 7 pages, including 2 figures. Talk presented by C. Giunti at TAUP97,
September 7-11, 1997, Laboratori Nazionali del Gran Sasso, Ital
Neutrino oscillations and the effect of the finite lifetime of the neutrino source
We consider a neutrino source at rest and discuss a condition for the
existence of neutrino oscillations which derives from the finite lifetime
of the neutrino source particle. This condition is present if the
neutrino source is a free particle such that its wave function is
non-stationary. For a Gaussian wave function and with some simplifying
assumptions, we study the modification of the usual oscillation probability
stemming from . In the present accelerator experiments the effect of
can be neglected. We discuss some experimental situations where the
source lifetime becomes relevant in the oscillation formula.Comment: 13 pages latex file with 2 figure
Precision Neutrino Oscillation Physics with an Intermediate Baseline Reactor Neutrino Experiment
We discuss the physics potential of intermediate km
baseline experiments at reactor facilities, assuming that the solar neutrino
oscillation parameters and lie in the
high-LMA solution region. We show that such an intermediate baseline reactor
experiment can determine both and with a
remarkably high precision. We perform also a detailed study of the sensitivity
of the indicated experiment to , which drives the
dominant atmospheric () oscillations, and to
- the neutrino mixing angle limited by the data from the CHOOZ and
Palo Verde experiments. We find that this experiment can improve the bounds on
. If the value of is large enough, \sin^2\theta
\gtap 0.02, the energy resolution of the detector is sufficiently good and if
the statistics is relatively high, it can determine with extremely high
precision the value of . We also explore the potential of
the intermediate baseline reactor neutrino experiment for determining the type
of the neutrino mass spectrum, which can be with normal or inverted hierarchy.
We show that the conditions under which the type of neutrino mass hierarchy can
be determined are quite challenging, but are within the reach of the experiment
under discussion.Comment: 25 page
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