Neutrino masses, mixing and hierarchy

Neutrino masses: hierarchy without hierarchy

A large hierarchy of the Dirac masses can result in a small hierarchy for the low energy masses of the active neutrinos. This can happen even if the Majorana masses of right-handed neutrinos are all equal. A realistic description of the observed neutrino masses and mixing can be obtained starting from a large hierarchy in the Dirac masses. A large mixing for solar neutrinos results from the neu...

Neutrino Masses and Mixing∗

The investigation of neutrino properties is a very important problem of today’s neutrino physics. The key problem is the problem of neutrino masses. If neutrinos are massive, they can be mixed. If the total lepton number is conserved, massive neutrinos are Dirac particles. If the neutrino masses are generated by an interaction that does not conserve the total lepton number, neutrinos with defin...

Neutrino masses and mixing

Status of determination of the neutrino masses and mixing is formulated and possible uncertainties, especially due to presence of the sterile neutrinos, are discussed. The data hint an existence of special “neutrino” symmetries. If not accidental these symmetries have profound implications and can substantially change the unification program. The key issue on the way to underlying physics is re...

Neutrino Masses and Mixing

I review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data. The result from the LSND experiment and the possible role of neutrinos as hot dark matter are also included. I also discuss the simplest schemes proposed to reconcile these data which include a light sterile neutrino in addition to the three standard ones. Implications for future experime...

Neutrino masses and mixing