A Unique Oscillation Solution to the Solar Neutrino Problem?

A global two-neutrino oscillation fit combining Super-Kamiokande solar neutrino data with the solar neutrino rates measured by Homestake, Gallex/GNO, SAGE and SNO prefers a single allowed area, the Large Mixing Angle solution, at about 95% confidence level. The mass^2 difference between the two mass eigenstates is Delta m^2 approx 3-25 x 10^-5 eV^2, the mixing angle theta is tan^2 theta approx 0.21-0.67.Comment: 10 pages, 3 figures, to be published in the proceedings of the NOON 2001 worksho

Neutrino-electron scattering in noncommutative space

Neutral particles can couple with the $U(1)$ gauge field in the adjoint representation at the tree level if the space-time coordinates are noncommutative (NC). Considering neutrino-photon coupling in the NC QED framework, we obtain the differential cross section of neutrino-electron scattering. Similar to the magnetic moment effect, one of the NC terms is proportional to $\frac 1 T$, where $T$ is the electron recoil energy. Therefore, this scattering provides a chance to achieve a stringent bound on the NC scale in low energy by improving the sensitivity to the smaller electron recoil energy.Comment: 12 pages, 2 figure

Resonant leptogenesis in a predictive SO(10) grand unified model

An SO(10) grand unified model considered previously by the authors featuring lopsided down quark and charged lepton mass matrices is successfully predictive and requires that the lightest two right-handed Majorana neutrinons be nearly degenerate in order to obtain the LMA solar neutrino solution. Here we use this model to test its predictions for baryogenesis through resonant-enhanced leptogenesis. With the conventional type I seesaw mechanism, the best predictions for baryogenesis appear to fall a factor of three short of the observed value. However, with a proposed type III seesaw mechanism leading to three pairs of massive pseudo-Dirac neutrinos, resonant leptogenesis is decoupled from the neutrino mass and mixing issues with successful baryogenesis easily obtained.Comment: 22 pages including 1 figure; published version with reference adde

Majorana Neutrino Mixing

The most plausible see-saw explanation of the smallness of the neutrino masses is based on the assumption that total lepton number is violated at a large scale and neutrinos with definite masses are Majorana particles. In this review we consider in details difference between Dirac and Majorana neutrino mixing and possibilities of revealing Majorana nature of neutrinos with definite masses

Status of global fits to neutrino oscillations

We review the present status of global analyses of neutrino oscillations, taking into account the most recent neutrino data including the latest KamLAND and K2K updates presented at Neutrino2004, as well as state-of-the-art solar and atmospheric neutrino flux calculations. We give the two-neutrino solar + KamLAND results, as well as two-neutrino atmospheric + K2K oscillation regions, discussing in each case the robustness of the oscillation interpretation against departures from the Standard Solar Model and the possible existence of non-standard neutrino physics. Furthermore, we give the best fit values and allowed ranges of the three-flavour oscillation parameters from the current worlds' global neutrino data sample and discuss in detail the status of the small parameters \alpha \equiv \Dms/\Dma as well as $\sin^2\theta_{13}$, which characterize the strength of CP violating effects in neutrino oscillations. We also update the degree of rejection of four-neutrino interpretations of the LSND anomaly in view of the most recent developments.Comment: v6: In the last Appendix we provide updated neutrino oscillation results which take into account the relevant oscillation data released by the MINOS and KamLAND collaboration