Narrow Results

Based on the independent measurements on neutrino mass splitting , and recent measurements by the T2K Collaboration, we carry out a simple fitting analysis on and in normal hierarchy and inverted hierarchy respectively, suggesting and in normal hierarchy, or and in inverted hierarchy. The simple analysis indicate that both normal and inverted hierarchies are consistent with current experimental measurements on mass splitting. The p-value for normal hierarchy and that for inverted hierarchy are 62% and 55%, respectively. This reveals a slight favor for the normal hierarchy. It is suggested that further measurements on the mass splitting with higher accuracy are necessary to determine the neutrino mass hierarchy.

The detection of galactic supernova (SN) neutrinos represents one of the future frontiers of low energy neutrino physics and astrophysics. The neutron coherence of neutral currents (NCs) allows quite large cross-sections in the case of neutron rich targets, which can be exploited in detecting earth and sky neutrinos by measuring nuclear recoils. They are relatively cheap and easy to maintain. These (NC) cross-sections are not dependent on flavor conversions and, thus, their measurement will provide useful information about the neutrino source. In particular, they will yield information about the primary neutrino fluxes and perhaps about the spectrum after flavor conversions in neutrino sphere. They might also provide some clues about the neutrino mass hierarchy. The advantages of large gaseous low threshold and high resolution time projection counters (TPC) detectors are discussed.

The present atmospheric neutrino oscillation data viewed within the context of see-saw mechanism for small neutrino masses, requires right handed neutrino masses (M_R) around the conventional GUT scale i.e. 10¹⁵ to 10¹⁶ GeV. This raises a new hierarchy puzzle i.e. why M_R ≪ M_Pl? This can be interpreted as an indication in favor of new local symmetries around M_R. In this paper, we argue that depending on the nature of neutrino mass patterns, this symmetry could either be: (i) the local B-L symmetry arising from a larger symmetry group such as in the left-right symmetric model of weak interactions, grand unified SO(10) models etc. or (ii) a local horizontal symmetry group SU(2)_H operating on the fermions of the first two generations which is often invoked to understand the generation puzzles. We discuss some simple consequences of these symmetries and propose experimental tests for these ideas.

The detection of galactic supernova (SN) neutrinos represents one of the future frontiers of low energy neutrino physics and astrophysics. The neutron coherence of neutral currents (NCs) allows quite large cross-sections in the case of neutron rich targets, which can be exploited in detecting earth and sky neutrinos by measuring nuclear recoils. They are relatively cheap and easy to maintain. These (NC) cross-sections are not dependent on flavor conversions and, thus, their measurement will provide useful information about the neutrino source. In particular, they will yield information about the primary neutrino fluxes and perhaps about the spectrum after flavor conversions in neutrino sphere. They might also provide some clues about the neutrino mass hierarchy. The advantages of large gaseous low threshold and high resolution time projection counters (TPC) detectors are discussed.