Pseudo-Dirac neutrinos as a potential complete solution to the neutrino oscillation puzzle

TL;DR

This paper proposes a neutrino oscillation model using pseudo-Dirac Majorana neutrinos that aligns with experimental data and offers a comprehensive solution to the neutrino puzzle, with implications for dark matter and future experiments.

Contribution

It introduces a pseudo-Dirac neutrino model that explains all neutrino oscillation data and discusses its implications for dark matter and experimental verification.

Findings

Compatible with all neutrino oscillation data

Addresses dark matter and Big Bang nucleosynthesis constraints

Suggests specific experimental tests for validation

Abstract

A solution for the neutrino mass and mixing pattern is proposed which is compatible with all available experimental data on neutrino oscillations. This solution involves Majorana neutrinos of the pseudo-Dirac type, i.e. m_Majorana << m_Dirac. The solar and atmospheric neutrino observations are mainly explained as nu_e - nu_e^S and nu_mu - nu_mu^S oscillations, where S indicates the sterile (``righthanded'') partner of each neutrino generation, while the LSND result is interpreted in terms of standard nu_mu - nu_e oscillations. The resulting constraints on nu_mu - nu_tau and nu_tau - nu_tau^S oscillations are also discussed. This solution leaves room for a hierarchical mass and mixing scheme with a nu_tau mass in the few eV range, as favoured by some dark matter scenarios. The apparent conflict with standard Big Bang nucleosynthesis is addressed and the implications for current and future experiments are discussed. It is argued that both short and long baseline accelerator neutrino experiments are needed in order to decide between this solution and other oscillation scenarios.