Assuming four-neutrino mixing and massive Majorana neutrinos, we study the implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems, of the results of the LSND experiment and of the constraints on neutrino oscillations, obtained in reactor and accelerator experiments, for the predictions of the effective Majorana mass in neutrinoless double beta ((ββ) 0ν...

Assuming four-neutrino mixing and massive Majorana neutrinos, we study the implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems, of the results of the LSND experiment and of the constraints on neutrino oscillations, obtained in reactor and accelerator experiments, for the predictions of the effective Majorana mass in neutrinoless double beta ((ββ) 0ν...

The possibility to determine the type of neutrino mass hierarchy by studying atmospheric neutrino oscillations with a detector capable to distinguish between neutrino and antineutrino events, such as magnetized iron calorimeters, is considered. We discuss how the ability to distinguish between the neutrino mass spectrum with normal and inverted hierarchy depends on detector characteristics like...

We argue that the evidence for neutrino mass is quite compelling. This mass raises a number of questions, which we enumerate, about neutrinos. Then we focus on one of these questions—the issue of the possible neutrino mass spectra. In particular, we explain that one can have a four-neutrino spectrum which does not require significant sterile-neutrino involvement in either the atmospheric or sol...

We present the generic formulas to calculate the ratios of neutrino masses and the Majorana phases of CP violation from the neutrino mass matrix with two independent vanishing entries in the flavor basis where the charged lepton mass matrix is diagonal. An order-of-magnitude illustration is given for seven experimentally acceptable textures of the neutrino mass matrix, and some analytical appro...

Thanks to very strong evidence that neutrinos oscillate [1], we now know that they almost certainly have masses and mix. That neutrinos have masses means that there is some spectrum of three or more neutrino mass eigenstates, ν1, ν2, ν3, . . ., which are the neutrino analogues of the charged-lepton mass eigenstates, e, μ, and τ . That neutrinos mix means that the weak interaction couples a give...

The four light neutrino scenario, which explains the atmosphere, solar and LSND neutrino experiments, is studied in the framework of singular seesaw mechanism. By taking the Dirac neutrino mass matrix to be also singular, the right-handed neutrino Majorana mass can be at 1014 GeV scale. Abelian flavor symmetry is used to produce the required neutrino mass pattern. Maximal mixings between the νμ...

I review promising approaches to neutrino mass models, focussing on three neutrino patterns of neutrino masses and mixing angles, and the corresponding Majorana mass matrices. I discuss the see-saw mechanism, and show how it may be applied in a very natural way to give a neutrino mass hierarchy with large atmospheric and solar angles by assuming single right-handed neutrino dominance. A theoret...

We investigate an alternative seesaw mechanism for neutrino mass generation. Neutrino mass is generated at loop level but the basic concept of usual seesaw mechanism is kept. One simple model is constructed to show how this mechanism is realized. The applications of this seesaw mechanism at weak scale to cosmology and neutrino physics are discussed. Seesaw mechanism [1] is one of the best and s...