Bounds on the Coupling of the Majoron to Light Neutrinos from Supernova Cooling

We explore the role of Majoron ($J$) emission in the supernova cooling process, as a source of upper bound on neutrino-Majoron coupling. We show that the strongest upper bound on the coupling to $\nu_e$ comes from the $\nu_e\nu_e \to J$ process in the core of a supernova. We also find bounds on diagonal couplings of the Majoron to $\nu_{\mu(\tau)}\nu_{\mu(\tau)}$ and on off-diagonal $\nu_e \nu_{\mu (\tau)}$ couplings in various regions of the parameter space. We discuss the evaluation of the cross-section for four-particle interactions ($\nu \nu \to JJ$ and $\nu J \to \nu J$). We show that these are typically dominated by three-particle sub-processes and do not give new independent constraints.Comment: 34 pages, Version to appear in Phys. Rev.

Effects of the neutrino B-term on the Higgs mass parameters and electroweak symmetry breaking

To embed the seesaw mechanism in the MSSM, two or three right-handed neutrino supermultiplets, $N_i$, have to be added to the model. In the presence of these new superfields, the soft supersymmetry breaking potential includes a lepton number violating mass term which is known as the neutrino $B$-term, $M B_\nu\tilde{N}\tilde{N}/2$. In this paper, we study the effects of $B_\nu$ on the Higgs mass parameters. Using the condition for the electroweak symmetry breaking, we derive an upper bound on $B_\nu$ which is two orders of magnitude stronger than the previous bounds. We also propose a simple model in which it is natural to have large values of $B_\nu$ while the rest of the supersymmetry breaking terms are at the TeV scale or smaller.Comment: 12 pages, 4 figure

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

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

Shedding light on LMA-Dark solar neutrino solution by medium baseline reactor experiments: JUNO and RENO-50

In the presence of Non-Standard neutral current Interactions (NSI) a new solution to solar neutrino anomaly with $\cos 2\theta_{12}<0$ appears. We investigate how this solution can be tested by upcoming intermediate baseline reactor experiments, JUNO and RENO-50. We point out a degeneracy between the two solutions when both hierarchy and the $\theta_{12}$ octant are flipped. We then comment on how this degeneracy can be partially lifted by long baseline experiments sensitive to matter effects such as the NOvA experiment.Comment: 9 pages, 2 figure