On vacuum oscillations solution of the solar neutrino problem

Experimental signatures of vacuum oscillations solution of the solar neutrino problem are considered. This solution predicts a strict correlation between a distortion of the neutrino energy spectrum and an amplitude of seasonal variations of the neutrino flux. The slope parameter which characterizes a distortion of the recoil electron energy spectrum in the Super-Kamiokande experiment and the seasonal asymmetry of the signal have been calculated in a wide range of oscillation parameters. The correlation of the slope and asymmetry gives crucial criteria for identification or exclusion of this solution. For the positive slope indicated by preliminary Super-Kamiokande data we predict (40 – 60) % enhancement of the seasonal variations.     

Testing the vacuum oscillation and the MSW solutions of the solar neutrino problem

Solar model independent tests of the vacuum oscillation and MSW solutions of the solar neutrino problem are considered. Detailed predictions for time (seasonal) variations of the signals due to neutrino oscillations in vacuum are given for the future solar neutrino detectors (SNO, Super-Kamiokande, BOREXINO, HELLAZ). Results on the distortions of the spectra of ⁸B neutrinos, and of e⁻ from the reaction ν + e⁻ → ν + e⁻ induced by ⁸B neutrinos, are presented in the cases of vacuum oscillations or MSW transitions for a large number of values of the relevant parameters. The possibilities to distinguish between the vacuum oscillation, the MSW adiabatic, and the MSW nonadiabatic transitions in the future solar neutrino experiments are discussed.     

A gut solution to the solar neutrino problem

Within the supersymmetric flipped SU(5)×U(1) model, we propose a mechanism for realization of the Voloshin-Vysotsky-Okun solution to the solar neutrino problem by attributing a large magnetic moment to the electron neutrino, as required to explain the solar neutrino data.     

Quantum dissipation in vacuum neutrino oscillation

The pattern of neutrino oscillations changes when one considers these particles evolving as an open quantum system. In this article we derive seven possibilities that change the two-generation neutrino survival probability due to quantum dissipation and decoherence. We find entirely original probabilities assuming that these effects can be parametrized by the addition of only one phenomenological constant keeping complete positivity. We observe that a relaxation effect of the system shows an unusual mechanism of flavor conversion, the appearance of CP-violation effects for Majorana neutrinos, besides an appreciable change in the behavior of high energy neutrinos.     

Conventional nuclear physics solution of the solar neutrino problem

A basic and inherently simple alternative explanation of the solar neutrino problem is proposed based upon conventional nuclear physics. Our results for the tunneling factor, astrophysicalS-factor, and our resolution are compared with rather speculative solutions commonly attempted by accepting the customary ingredients of the standard solar model. We present a more realistic solution of nuclear Coulomb barrier tunneling together with a more precise parametric representation of the astrophysical functionS. We determineS from high-energy (>100 keV)⁷Be(p, )⁸B experimental cross-section data using the new tunneling factor. This leads to a low-energy fusion cross section that is lower than previous estimates by 26–36%, decreasing the anticipated neutrino flux close to experimentally detected values. This may resolve the missing solar neutrino flux problem.     

SNO results and neutrino magnetic moment solution to the solar neutrino problem

We have analysed the solar neutrino data obtained from chlorine, gallium and Super-Kamiokande (SK) experiments (1258 days) and also the new results that came from Sudbury Neutrino Observatory (SNO) charge current (CC) and elastic scattering (ES) experiments considering that the solar neutrino deficit is due to the interaction of neutrino transition magnetic moment with the solar magnetic field. We have also analysed the moments of the spectrum of scattered electrons at SK. Another new feature in the analysis is that for the global analysis, we have replaced the spectrum by its centroid.     

Updated solution to the solar neutrino problem based on non-standard neutrino interactions

We present an updated version of the solution to the solar neutrino problem based on non-standard flavor changing neutrino interactions (FCNI) and non-universal flavor diagonal neutrino interactions (FDNI). We find a good fit not only to the total rates measured by all solar neutrino experiments but also to the day-night and seasonal variations of the event rate, as well as the recoil electron energy spectrum measured by the SuperKamiokande collaboration.     

Gravitational effects on the neutrino oscillation in vacuum

The propagation of neutrinos in a gravitational field is studied by developing a method of calculating a covariant quantum-mechanical phase in a curved space-time. The result is applied to neutrino propagation in the Schwarzschild metric.     

The effect of random matter density perturbations on the MSW solution to the solar neutrino problem

We consider the implications of solar matter density random noise upon resonant neutrino conversion. The evolution equation describing MSW-like conversion is derived in the framework of the Schrödinger approach. We study quantitatively the effect of such matter perturbations upon both large and small mixing angle MSW solutions to the solar neutrino problem. This is carried out both for the active-active v_e → v_μ,τ as well as active-sterile v_e → v_s conversion channels. We find that the small mixing MSW solution is much more stable (especially in Δm² than the large mixing solution. The possible existence of solar matter density noise at the few percent level could be tested at future solar neutrino experiments, especially Borexino.     

Solutions to the solar neutrino problem

Several well known neutrino physics solutions to the solar neutrino problem are briefly reviewed and their status in the light of the latest experimental data is presented.     

Neutrino magnetic moment solution for the solar neutrino problem and the SNO experiment

The motivations for the magnetic moment solution to the solar neutrino problem are briefly reviewed and the expected values for a number of observables to be measured by the SNO experiment are calculated assuming three different solar magnetic field profiles. The observables examined are the charged current event rate, the ratio of the neutral current to the charged current event rates and the charged current electron spectrum as well as their first and second moments. The dependence of results on the hep neutrino flux is also analysed and a comparison is made with the corresponding oscillation results.