Searcharxiv⌕ Search

arXiv subjects

C. Giunti

Publications and source records attributed to C. Giunti.

At least 163 records · Page 9Linked to original sources
arXiv1997

Constraints on neutrinoless double beta decay from neutrino oscillation experiments

We show that, in the framework of a general model with mixing of three Majorana neutrinos and a neutrino mass hierarchy, the results of the Bugey and Krasnoyarsk reactor neutrino oscillation experiments imply strong limitations for the effective Majorana mass | | that characterizes the amplitude of neutrinoless double beta decay. We obtain further limitations on | | from the data of the atmospheric neutrino experiments. We discuss the possible implications of the results of the future long baseline neutrino oscillation experiments for neutrinoless double beta decay.

hep-ph↗
arXiv1996

Gravitational Effects on the Neutrino Oscillation

The propagation of neutrinos in a gravitational field is studied. A method of calculating a covariant quantum-mechanical phase in a curved space-time is presented. The result is used to calculate gravitational effects on the neutrino oscillation in the presence of a gravitational field. We restrict our discussion to the case of the Schwartzschild metric. Specifically, the cases of the radial propagation and the non-radial propagation are considered. A possible application to gravitational lensing of neutrinos is also suggested.

hep-ph↗
arXiv1996

Possible tests of the "strangeness" of the nucleon

The NC and CC scattering of neutrino(antineutrino) on protons and nuclei with isotopic spin equal to zero is considered. It is shown that the measurement of the neutrino-antineutrino asymmetry in these processes could allow to obtain model-independent information about the contribution of the axial strange current to the cross sections of the NC processes.

hep-ph↗
arXiv1996

Inclusive neutrino and antineutrino processes and the problem of the spin of proton

The inclusive NC and CC neutrino(antineutrino)-nucleus scattering for the case of a nucleus with isotopic spin equal to zero is considered. It is shown that the measurement of the neutrino-antineutrino asymmetry at relatively small energies could allow to obtain model-independent information about the contribution of the axial strange current to the cross sections of the NC processes.

hep-ph↗
arXiv1996

Neutrino mass spectrum from the results of neutrino oscillation experiments

All the possible schemes of neutrino mixing with four massive neutrinos inspired by the existing experimental indications in favor of neutrino mixing are considered in a model independent way. Assuming that in short-baseline experiments only one mass-squared difference is relevant, it is shown that the scheme with a neutrino mass hierarchy is not compatible with the experimental results. Only two schemes with two pairs of neutrinos with close masses separated by a mass difference of the order of 1 eV are in agreement with the results of all experiments. One of these schemes leads to possibly observable effects in Tritium and neutrinoless double-beta decay experiments.

hep-ph↗
arXiv1996

Short-baseline neutrino oscillations and neutrinoless double-beta decay in schemes with an inverted mass spectrum

We have considered short-baseline neutrino oscillations, tritium beta-decay and neutrinoless double-beta decay in two schemes with an inverted mass spectrum and mixing of three and four massive neutrino fields. We have analyzed the results of the latest experiments on the search for oscillations of terrestrial neutrinos and we have discussed the compatibility of the LSND indication in favor of neutrino oscillations with the results of the other experiments. In the framework of the models under consideration, it is shown that the observation of neutrinoless double-beta decay could allow to obtain information about the CP violation in the lepton sector.

hep-ph↗
arXiv1996

Possible tests of neutrino maximal mixing and comments on matter effects

We show in a simple and general way that matter effects do not contribute to the averaged value of the probabilities of transition of solar $ν_e$'s into other states in the case of maximal mixing of any number of massive neutrinos. We also show that future solar neutrino experiments (Super-Kamiokande and SNO) will allow to test the model with maximal mixing of three massive neutrinos in a way that does not depend on the initial solar neutrino flux.

hep-ph↗
arXiv1996

Short-baseline neutrino oscillations and neutrinoless double-beta decay in the framework of three neutrino mixing and a mass hierarchy

We have analyzed the results of the latest terrestrial neutrino oscillation experiments in the framework of a model with mixing of three massive neutrinos and a neutrino mass hierarchy ($ m_1 << m_2 << m_3 $). In this model, oscillations of the terrestrial neutrinos are characterized by three parameters, $ Δm^2 = m_3^2 - m_1^2 $ and the squared moduli of the two mixing matrix elements $U_{e3}$ and $U_{\mu3}$. Using the results of disappearance experiments and solar neutrino experiments, it is shown that only two regions of possible values of $|U_{e3}|^2$ and $|U_{\mu3}|^2$ are allowed: I. $|U_{e3}|^2$ and $|U_{\mu3}|^2$ are both small and II. $|U_{e3}|^2$ is small and $|U_{\mu3}|^2$ is large. If the mixing parameters are in the region I, $ ν_μ<-> ν_e $ oscillations are suppressed. In this case the LSND indication in favor of $ ν_μ<-> ν_e $ oscillations is not compatible with the negative results of all other experiments. If the mixing parameters are in the region II, $ ν_e <-> ν_τ$ oscillations are strongly suppressed. If massive neutrinos are Majorana particles, our analysis shows that neutrinoless double-beta decay could be observed in the experiments of the next generation only if the mixing parameters are in the region I.

hep-ph↗
arXiv1995

Neutrino oscillations with three-generation mixings and mass hierarchy

We have analyzed the results of reactor and accelerator neutrino oscillation experiments in a model with mixing of three neutrino fields and a neutrino mass hierarchy. It is shown that $ ν_μ\leftrightarrows ν_e $ oscillations with $ 0.6 \le Δm^2 \le 100 \, \mathrm{eV}^2 $ and amplitude larger than $ 2 \times 10^{-3} $ are not compatible with the existing limits on neutrino oscillations if the non-diagonal elements of the mixing matrix are small. Thus, if the excess of positron events recently observed in the LSND experiment is due to $ \barν_μ\to \barν_e $ oscillations, the mixing in the lepton sector is basically different from the CKM mixing of quarks.

hep-ph↗
arXiv1995

Possible tests for sterile neutrinos

It is shown that the future SNO and Super-Kamiokande experiments, in which high energy $^8\mathrm{B}$ neutrinos will be detected through the observation of CC, NC and $ν$--$e$ 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.

hep-ph↗
arXiv1995

Elastic Neutrino-Nucleon and Antineutrino-Nucleon Scattering and Strange Form Factors of the Nucleons

Elastic scattering of neutrinos and antineutrinos on nucleons is considered. It is shown that the measurement of the neutrino-antineutrino asymmetry would allow to obtain model independent informations on the strange axial and vector form factors. The ratio of the magnetic form factors of the proton and neutron, on which the asymmetry depends, is investigated in detail. The asymmetry is calculated under different assumptions on the behavior of the strange vector and axial form factors.

hep-ph↗
arXiv1995

Neutrino Oscillations in the Framework of Three-Generation Mixings with Mass Hierarchy

We have analyzed the results of reactor and accelerator neutrino oscillation experiments in the framework of a general model with mixing of three neutrino fields and a neutrino mass hierarchy that can accommodate the results of the solar neutrino experiments. It is shown that $ ν_μ\leftrightarrows ν_e $ oscillations with $ 0.6 \le Δm^2 \le 100 \, \mathrm{eV}^2 $ and amplitude larger than $ 2 \times 10^{-3} $ are not compatible with the existing limits on neutrino oscillations if the non-diagonal elements of the mixing matrix $ \left| U_{e3} \right| $ and $ \left| U_{\mu3} \right| $ are small. Thus, if the excess of electron events recently observed in the LSND experiment is due to $ ν_μ\leftrightarrows ν_e $ oscillations, the mixing in the lepton sector is basically different from the CKM mixing of quarks. If this type of mixing is realized in nature, the observation of $ ν_μ\leftrightarrows ν_e $ oscillations would not influence $ ν_μ\leftrightarrows ν_τ$ oscillations that are being searched for in the CHORUS and NOMAD experiments.

hep-ph↗
arXiv1995

Atmospheric Neutrino Oscillations among Three Neutrino Flavors and Long-Baseline Experiments

Anticipating future long-baseline neutrino experiments to search for neutrino oscillations in various oscillation channels, we have analyzed the atmospheric neutrino data in the framework of a model with mixing of three massive neutrino fields that can accommodate the data of solar neutrino experiments. The oscillations of atmospheric and terrestrial neutrinos are described in this model by three parameters: $ Δm^2 $ and the squared moduli of two elements of the mixing matrix, $ | U_{e3} |^2 $ and $ | U_{\mu3} |^2 $, which determine the amplitudes of oscillations among all active neutrinos. The results of the analysis of the atmospheric neutrino data are presented in the form of allowed regions in the plane of the two parameters oscillation amplitude and $ Δm^2 $ for all oscillation channels to be investigated in the future long-baseline oscillation experiments.

hep-ph↗
arXiv1995

Some Remarks on Nu(mu)-Nu(e) Oscillations of Terrestrial Neutrinos and Atmospheric Neutrino Oscillations

We present the results of an analysis of the data of reactor and accelerator neutrino oscillation experiments in the framework of a model with mixing of three massive neutrino fields and a neutrino mass hierarchy. The results of the LSND experiment are commented. Taking into account future long-baseline neutrino oscillation experiments, we have also analyzed the atmospheric neutrino data in the framework of the model.

hep-ph↗
arXiv1995

ARE THERE STERILE NEUTRINOS IN THE FLUX OF SOLAR NEUTRINOS ON THE EARTH?

It is shown that the future SNO and Super-Kamiokande experiments, in which high energy $^8\mathrm{B}$ neutrinos will be detected through the observation of CC, NC and $ν$--$e$ 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. Lower bounds for different averaged values of the probability of transition of solar $ν_e$'s into sterile states and for the total flux of $^8\mathrm{B}$ neutrinos are derived in terms of measurable quantities. The possibilities to reveal the presence of $ν_μ$ and/or $ν_τ$ in the solar neutrino flux on the earth are also considered and the case of transitions of solar $ν_e$'s only into sterile states is discussed. Some numerical results for a simple model with $ν_e$--$ν_s$ mixing are given.

hep-ph↗