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.     

First evidence of pep solar neutrinos by direct detection in Borexino

We observed, for the first time, solar neutrinos in the 1.0-1.5 MeV energy range. We determined the rate of pep solar neutrino interactions in Borexino to be 3.1±0.6{stat}±0.3{syst} counts/(day·100 ton). Assuming the pep neutrino flux predicted by the standard solar model, we obtained a constraint on the CNO solar neutrino interaction rate of <7.9 counts/(day·100 ton) (95% C.L.). The absence of the solar neutrino signal is disfavored at 99.97% C.L., while the absence of the pep signal is disfavored at 98% C.L. The necessary sensitivity was achieved by adopting data analysis techniques for the rejection of cosmogenic {11}C, the dominant background in the 1-2 MeV region. Assuming the Mikheyev-Smirnov-Wolfenstein large mixing angle solution to solar neutrino oscillations, these values correspond to solar neutrino fluxes of (1.6±0.3)×10{8} cm{-2}?s^{-1} and <7.7×10{8} cm{-2}?s{-1} (95% C.L.), respectively, in agreement with both the high and low metallicity standard solar models. These results represent the first direct evidence of the pep neutrino signal and the strongest constraint of the CNO solar neutrino flux to date.     

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.     

Neutrino-lepton masses, Zee scalars, and muon g-2

Evidence for neutrino oscillations points to the existence of tiny but finite neutrino masses. Such masses may be naturally generated via radiative corrections in models, such as the Zee model, where a singlet Zee scalar plays a key role. We minimally extend the Zee model by including a right-handed singlet neutrino nu(R). The radiative Zee mechanism can be protected by a simple U(1)(X) symmetry involving only the nu(R) and a Zee scalar. We further construct a class of models with a single horizontal U(1)(FN) (à la Froggatt-Nielsen) such that the mass patterns of the neutrinos and leptons are naturally explained. We then analyze the muon anomalous magnetic moment (g(mu)-2) and the flavor changing mu-->egamma decay. The nu(R) interaction in our minimal extension is found to induce the BNL g(mu)-2 anomaly, with a light charged Zee scalar of mass 100-300 GeV.     

MHD fluctuations and low energy solar neutrinos

We analyze here how future solar neutrino experiments could detect neutrino flux fluctuations due to magnetohydrodynamics (MHD) perturbations on the solar plasma. We state that if such time fluctuations are detected, this would provide a unique signature of the resonant spin-flavor precession (RSFP) mechanism as a solution to the solar neutrino problem. Received: 2 July 2001 / Revised version: 4 April 2002 / Published online: 20 August 2002     

Majorana neutrino transition magnetic moment in a variant of Zee model with horizontal symmetry

A SU(2) _H symmetric variant of Zee model of lepton flavor violation is presented and is shown to lead to neutrino transition magnetic moment of the order required to explain the solar neutrino deficit and the possible anticorrelation of solar neutrino flux with sunspot activity via VVO mechanism. The use of horizontal symmetry leads to totally degenerate neutrino states which may be combined to form a ZKM Dirac neutrino with naturally small mass.     

Solving Solar Neutrino Puzzle via LMA MSW Conversion

We analyze the existing solar neutrino experiment data and show the allowed regions. The result from SNO＇s salt phase itself restricts quite a lot the allowed region＇s area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is excluded.     

Resonant spin-flavor precession constraints on the neutrino parameters and the twisting structure of the solar magnetic fields from the solar neutrino data

Resonant spin-flavor precession (RSFP) scenario with twisting solar magnetic fields has been confronted with the solar neutrino data from various ongoing experiments. The anticorrelation apparent in the Homestake solar neutrino data has been taken seriously to constrain (Δ m ² ,φ′) parameter space and the twisting profiles of the magnetic field in the convective zone of the Sun. The twisting profiles, thus derived, have been used to calculate the variation of the neutrino detection rates with the solar magnetic activity for the Homestake, Super-Kamiokande and the gallium experiments. It is found that the presence of twisting reduces the degree of anticorrelation in all the solar neutrino experiments. However, the anticorrelation in the Homestake experiment is expected to be more pronounced in this scenario. Moreover, the anticorrelation of the solar neutrino flux emerging from the southern solar hemisphere is expected to be stronger than that for the neutrinos emerging from the northern solar hemispheres.     

MHD origin of density fluctuations deep within the Sun and their influence on neutrino oscillation parameters in LMA MSW scenario

We analyze helioseismic waves near the solar equator in the presence of magnetic fields deep within the solar radiative zone. We find that reasonable magnetic fields can significantly alter the shapes of the wave profiles for helioseismic g modes. They can do so because the existence of density gradients allows g modes to resonantly excite Alfvén waves, causing mode energy to be funneled along magnetic field lines, away from the solar equatorial plane. The resulting waveforms show comparatively sharp spikes in the density profiles at radii where these resonances take place. Such matter density waves with known spatial structure are substituted as a matter density noise into the 2×2 Schrödinger equation for ν _e,π neutrinos oscillating within the Sun. Then we reexamine the sensitivity of solar neutrino oscillations to noise in the solar interior using the best current estimates of neutrino properties. Our results show that the measurement of neutrino properties at KamLAND provides new information about fluctuations in the solar environment on scales to which standard helioseismology constraints are largely insensitive. We also show how the determination of neutrino oscillation parameters from a combined fit of KamLAND and solar data depends strongly on the magnitude of solar density fluctuations.     

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)相似文献   

Matter effects in active-sterile solar neutrino oscillations

We study the matter effects for solar neutrino oscillations in a general scheme, without any constraint on the number of sterile neutrinos and the mixing matrix elements, only assuming a realistic hierarchy of neutrino squared-mass differences in which the smallest squared-mass difference is effective in solar neutrino oscillations. The validity of the analytic results is illustrated with a numerical solution of the evolution equation in the simplest case of four-neutrino mixing with the realistic matter density profile inside the Sun.     

Emission of neutrinos by alternating fields

It is supposed that the effective Lagrangian of interaction of a magnetic field with a neutrino can be written in the form $$L_{eff} = \frac{{G_{\mathbf{\gamma }} }}{{m_W^2 }} \frac{{\partial ^2 A^\mu }}{{\partial x^v \partial x_v }}[\bar \Psi _v {\mathbf{\gamma }}_\mu (1 + {\mathbf{\gamma }}^5 )\Psi _v ].$$ Formulas are obtained for the emission of neutrinos by alternating fields. In particular, neutrino synchrotron emission and neutrino emission in the case of collision of two classical charges are considered. Arguments are presented that this mechanism can make a contribution to the neutrino luminosity of stars.     

Constraining the spectrum of supernova neutrinos from nu-process induced light element synthesis

We constrain energy spectra of supernova neutrinos through the avoidance of an overproduction of the 11B abundance during Galactic chemical evolution. In supernova nucleosynthesis calculations with a parametrized neutrino spectrum as a function of temperature of nu(mu,tau) and nu(mu,tau) and total neutrino energy, we find a strong neutrino temperature dependence of the 11B yield. When the yield is combined with observed abundances, the acceptable range of the nu(mu,tau) and nu(mu,tau) temperature is found to be 4.8 to 6.6 MeV. Nonzero neutrino chemical potentials would reduce this temperature range by about 10% for a degeneracy parameter eta(nu) = mu(nu)/kT(nu) smaller than 3.     

The Implication of Kamiokande-Ⅱ Sun Neutrino Data

The cross section of B solar neutrino scattering involving the contribution of neutrino magnetic moment (NMM) is investigated. The constraints on the probability of flip of neutrino helicity and the possible value of NMM are extracted from the Kamiokande-II solar neutrino data and calculated cross section of v_e, scattering. It is found that the probability of neutrino helicity flip allowed by the Kamiokande-Ⅱ data may be small, which would be difficult to understand the ³⁷Cl data.     

Resonant neutrino oscillations and the neutrino signature of supernovae

We examine the effects of resonant neutrino oscillations, proposed as a solution to the solar neutrino puzzle, on the neutrino signature of a Type II supernova. We find that, for parameters corresponding to an adiabatic conversion of most of the ⁸B neutrino flux, the supernova neutrino signal in a water-Čerenkov detector is altered in the following way: (1) The isotropic-to-directional event ratio increases; (2) The short time scale neutronization burst signal decreases by a factor 7, perhaps rendering it unobservable. Detection of these changes would allow one to distinguish between neutrino oscillations and solar model alterations as solutions to the solar neutrino problem. We also note that mixing of the higher energy ν_μ and ν_r's to ν_e's will enhance detection of the thermally produced ν-flux.     

Limit on the electron neutrino magnetic moment from the kuo-sheng reactor neutrino experiment

A search of neutrino magnetic moment was carried out at the Kuo-Sheng Nuclear Power Station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg(-1) keV(-1) day(-1) at 12-60 keV were achieved. Based on 4712 and 1250 h of reactor ON and OFF data, respectively, the limit on the neutrino magnetic moment of mu(nu;(e))<1.3x10(-10)mu(B) at 90% confidence level was derived. An indirect bound of the nu;(e) radiative lifetime of m(3)(nu)tau(nu)>2.8x10(18) eV(3) s can be inferred.     

Direct measurement of the 7Be solar neutrino flux with 192 days of borexino data

We report the direct measurement of the 7Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso. The interaction rate of the 0.862 MeV 7Be neutrinos is 49+/-3stat+/-4syst counts/(day.100 ton). The hypothesis of no oscillation for 7Be solar neutrinos is inconsistent with our measurement at the 4sigma C.L. Our result is the first direct measurement of the survival probability for solar nu(e) in the transition region between matter-enhanced and vacuum-driven oscillations. The measurement improves the experimental determination of the flux of 7Be, pp, and CNO solar nu(e), and the limit on the effective neutrino magnetic moment using solar neutrinos.     

Topological geometrodynamics and the solar neutrino problem

A solution of the solar neutrino problem based on certain differences between T(opological) G(eometro) D(ynamics) and the standard model of the electroweak interactions is proposed. First, TGD predicts the existence of a right-handed neutrino inert with respect to ordinary electroweak interactions. Second, the generalization of the massless Dirac equation contains terms mixing differentM ⁴ chiralities, unlike the ordinary massless Dirac equation. This and the observation of anticorrelations of the solar neutrino flux with sunspot number suggest that solar neutrinos are transformed to right-handed neutrinos on the convective zone of the Sun. Third, the compactness ofCP ₂ implies topological field quantization: space-time decomposes into regions, topological field quanta, characterized by a handful of vacuum quantum numbers. In particular, there are topological obstructions for the smooth global imbeddings of magnetic fields and the decomposition of the solar magnetic field into flux tubes is predicted. Finally, every electromagnetically neutral mass distribution is accompanied by a long-rangeZ ⁰ vacuum field. If the vacuum quantum numbers inside the flux tubes of the solar magnetic field are considerably smaller than in the normal phase, theZ ⁰ electric force becomes strong and implies Thomas precession for the spin of the lefthanded component of the neutrino. As a consequence, left-handed neutrinos are transformed to right-handed ones and the process is irreversible, since righthanded neutrinos do not couple toZ ⁰.     

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.     

Superstring induced mass and magnetic moment of the neutrino and the time modulation of the solar neutrino flux

The new Yukawa couplings involving heavy matter E₆ fields predicted in the framework of superstring theories are considered as a source of mass and magnetic moment for the neutrino. Given the experimental bound m_ve < 46 eV bounds are derived on the neutrino magnetic moment thus generated. Finally, a scenario is produced where the induced magnetic moment has the correct magnitude (∼10⁻¹¹ μ_B) to explain an alleged depletion or solar neutrino flux during periods of maximum solar activity.