MHD solar fluctuations and solar neutrinos

We analyze how solar neutrino experiments could detect time fluctuations of the solar neutrino flux due to magnetohydrodynamic (MHD) perturbations of 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.707774Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Effects of non-standard neutrino interactions on MSW-LMA solution to the solar neutrino problem

We show that the non-standard neutrino interactions can play a role as sub-leading effect on the solar neutrino oscillations. We observe that very small flavor universality violations of order of 0.1-0.2 G_F is sufficient to induce two phenomena: suppression of the eletronic neutrino earth regeneration and a shift of the resonance layer in the sun. We obtain these phenomena even in the absence of any flavor changing interactions. We discuss their consequences and confront with a global analysis of solar+KamLAND results. We conclude that a new compatibility region in the Delta m^2 x tan^2\theta, which we call very low Large Mixing Angle region, is found for Delta m^2 ~ 1e-5 eV^2 and tan^2\theta= 0.45.Comment: references added, small changes in text, some changes in predictions of KamLAND future sensitivity to NSNI parameter

Toward precision measurements in solar neutrinos

Solar neutrino physics enters a stage of precision measurements. In this connection we present a precise analytic description of the neutrino conversion in the context of LMA MSW solution of the solar neutrino problem. Using the adiabatic perturbation theory we derive an analytic formula for the $\nu_e$ survival probability which takes into account the non-adiabatic corrections and the regeneration effect inside the Earth. The probability is averaged over the neutrino production region. We find that the non-adiabatic corrections are of the order $10^{-9}-10^{-7}$. Using the formula for the Earth regeneration effect we discuss features of the zenith angle dependence of the $\nu_e$ flux. In particular, we show that effects of small structures at the surface of the Earth can be important.Comment: 26 pages, 6 figures. Version to appear in Nucl. Phys.

Radiative Generation of the LMA Solution from Small Solar Neutrino Mixing at the GUT Scale

We show that in see-saw models with small or even vanishing lepton mixing angle $\theta_{12}$, maximal $\theta_{23}$, zero $\theta_{13}$ and zero CP phases at the GUT scale, the currently favored LMA solution of the solar neutrino problem can be obtained in a rather natural way by Renormalization Group effects. We find that most of the running takes place in the energy ranges above and between the see-saw scales, unless the charged lepton Yukawa couplings are large, which would correspond to a large $\tan \beta$ in the Minimal Supersymmetric Standard Model (MSSM). The Renormalization Group evolution of the solar mixing angle $\theta_{12}$ is generically larger than the evolution of $\theta_{13}$ and $\theta_{23}$. A large enhancement occurs for an inverted mass hierarchy and for a regular mass hierarchy with $|m_2 - m_1| \ll |m_2 + m_1|$. We present numerical examples of the evolution of the lepton mixing angles in the Standard Model and the MSSM, in which the current best-fit values of the LMA mixing angles are produced with vanishing solar mixing angle $\theta_{12}$ at the GUT scale.Comment: 10 pages, 6 figures; reference added, minor changes in the text; results unchanged; final version to appear in JHE

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.Comment: 6 eps figure

The Majorana Neutrino Mass Matrix with One Texture Zero and One Vanishing Eigenvalue

Possible patterns of the Majorana neutrino mass matrix $M$ with one texture zero and one vanishing eigenvalue are classified and discussed. We find that three one-zero textures of $M$ with $m_1 =0$ and four one-zero textures of $M$ with $m_3 =0$ are compatible with current neutrino oscillation data. The implications of these phenomenological ans$\rm\ddot{a}$tze on the neutrino mass spectrum and the neutrinoless double beta decay are also explored in some detail.Comment: RevTex 10 pages (with 2 PS figues). More discussions and references adde

Solar Neutrinos Before and After KamLAND

We use the recently reported KamLAND measurements on oscillations of reactor anti-neutrinos, together with the data of previously reported solar neutrino experiments, to show that: (1) the total 8B neutrino flux emitted by the Sun is 1.00(1.0 \pm 0.06) of the standard solar model (BP00) predicted flux, (2) the KamLAND measurements reduce the area of the globally allowed oscillation regions that must be explored in model fitting by six orders of magnitude in the Delta m^2-tan^2 theta plane, (3) LMA is now the unique oscillation solution to a CL of 4.7sigma, (4) maximal mixing is disfavored at 3.1 sigma, (5) active-sterile admixtures are constrained to sin^2 eta<0.13 at 1 sigma, (6) the observed ^8B flux that is in the form of sterile neutrinos is 0.00^{+0.09}_{-0.00} (1 sigma), of the standard solar model (BP00) predicted flux, and (7) non-standard solar models that were invented to completely avoid solar neutrino oscillations are excluded by KamLAND plus solar at 7.9 sigma . We also refine quantitative predictions for future 7Be and p-p solar neutrino experiments.Comment: Published version, includes editorial improvement

Low scale gravity as the source of neutrino masses?

We address the question whether low-scale gravity alone can generate the neutrino mass matrix needed to accommodate the observed phenomenology. In low-scale gravity the neutrino mass matrix in the flavor basis is characterized by one parameter (the gravity scale M_X) and by an exact or approximate flavor blindness (namely, all elements of the mass matrix are of comparable size). Neutrino masses and mixings are consistent with the observational data for certain values of the matrix elements, but only when the spectrum of mass is inverted or degenerate. For the latter type of spectra the parameter M_{ee} probed in double beta experiments and the mass parameter probed by cosmology are close to existing upper limits.Comment: 10 pages, 1 figur

Minimal archi-texture for neutrino mass matrices

The origin of the observed masses and mixing angles of quarks and leptons is one of imperative subjects in and beyond the standard model. Toward a deeper understanding of flavor structure, we investigate in this paper the minimality of fermion mass (Yukawa) matrices in unified theory. That is, the simplest matrix form is explored in light of the current experimental data for quarks and leptons, including the recent measurements of quark CP violation and neutrino oscillations. Two types of neutrino mass schemes are particularly analyzed; (i) Majorana masses of left-handed neutrinos with unspecified mechanism and (ii) Dirac and Majorana masses introducing three right-handed neutrinos. As a result, new classes of neutrino mass matrices are found to be consistent to the low-energy experimental data and high-energy unification hypothesis. For distinctive phenomenological implications of the minimal fermion mass textures, we discuss flavor-violating decay of charged leptons, the baryon asymmetry of the universe via thermal leptogenesis, neutrino-less double beta decay, and low-energy leptonic CP violation.Comment: 37 pages, 6 figure

Prediction of Ue3U_{e3} in Neutrino Mass Matrix with Two Zeros

We have discussed predictions of $|U_{e3}|$ and $J_{CP}$ in the framework of the neutrino mass matrix with two zeros. In the case of the best fit values of $\tan^2\theta_{12}$, $\tan^2\theta_{23}$, $\Delta m^2_{\rm sun}$ and $\Delta m_{\rm atm}^2$, the prediction of $|U_{e3}|$ is $0.11\sim 0.14$. The lower bound of $|U_{e3}|$ is 0.05, which depends on $\tan\theta_{12}$ and $\tan\theta_{23}$. We have investigated the stability of these predictions taking account of small corrections to zeros, which may come from radiative corrections or off-diagonal elements of the charged lepton massmatrix. The lower bound of $|U_{e3}|$ comes down considerably due to the small corrections to zeros.Comment: Figures and discussions are adde