A model for large non-standard interactions of neutrinos leading to the LMA-Dark solution

It is well-known that in addition to the standard LMA solution to solar anomaly, there is another solution called LMA-Dark which requires Non-Standard Interactions (NSI) with effective couplings as large as the Fermi coupling. Although this solution satisfies all the bounds from various neutrino oscillation observations and even provides a better fit to low energy solar neutrino spectrum, it is not as popular as the LMA solution mainly because no model compatible with the existing bounds has been so far constructed to give rise to this solution. We introduce a model that provides a foundation for such large NSI with strength and flavor structure required for the LMA-Dark solution. This model is based on a new $U(1)^\prime$ gauge interaction with a gauge boson of mass $\sim 10$ MeV under which quarks as well as the second and third generations of leptons are charged. We show that observable effects can appear in the spectrum of supernova and high energy cosmic neutrinos. Our model predicts a new contribution to the muon magnetic dipole moment and new rare meson decay modes.Comment: 10 page; References and more phenomenological bounds added; Results unchange

Measuring Dirac CP-violating phase with intermediate energy beta beam facility

Taking the established nonzero value of $\theta_{13}$, we study the possibility of extracting the Dirac CP-violating phase by a beta beam facility with a boost factor $100<\gamma<450$. We compare the performance of different setups with different baselines, boost factors and detector technologies. We find that an antineutrino beam from $^6$He decay with a baseline of $L=1300$ km has a very promising CP discovery potential using a 500 kton Water Cherenkov (WC) detector. Fortunately this baseline corresponds to the distance between FermiLAB to Sanford underground research facility in South Dakota.Comment: 14 pages, 7 figure

Implications of the Pseudo-Dirac Scenario for Ultra High Energy Neutrinos from GRBs

The source of Ultra High Energy Cosmic Rays (UHECR) is still an unresolved mystery. Up until recently, sources of Gamma Ray Bursts (GRBs) had been considered as a suitable source for UHECR. Within the fireball model, the UHECR produced at GRBs should be accompanied with a neutrino flux detectable at the neutrino telescope such as IceCube. Recently, IceCube has set an upper bound on the neutrino flux accompanied by GRBs about 3.7 times below the prediction. We investigate whether this deficit can be explained by the oscillation of the active neutrinos to sterile neutrinos en route from the source to the detectors within the pseudo-Dirac scenario. We then discuss the implication of this scenario for diffuse supernova relic neutrinos.Comment: 14 pages, 5 figures; v2: figures added, discussion improved, matches the version published in JCA

A Framework to Simultaneously Explain Tiny Neutrino Mass and Huge Missing Mass Problem of the Universe

Recently a minimalistic scenario has been developed to explain dark matter and tiny but nonzero neutrino masses. In this scenario, a new scalar called SLIM plays the role of the dark matter. Neutrinos achieve Majorana mass through a one-loop diagram. This scenario can be realized for both real and complex SLIM. Simultaneously explaining the neutrino mass and dark matter abundance constrains the scenario. In particular for real SLIM, an upper bound of a few MeV on the masses of the new particles and a lower bound on their coupling are obtained which make the scenario testable. The low energy scenario can be embedded within various $SU(2)\times U(1)$ symmetric models. I shall briefly review the scenario and a specific model that embeds the scenario, with special emphasis on the effects in the charged Kaon decay which might be observable at the KLOE and NA62 experiments.Comment: 7 pages, 1 figur