Type II Seesaw and a Gauge Model for the Bimaximal Mixing Explanation of Neutrino Puzzles

TL;DR

This paper introduces a gauge model utilizing Type II Seesaw and specific symmetries to naturally produce bimaximal neutrino mixing, explaining solar and atmospheric neutrino data without right-handed neutrinos.

Contribution

The model uniquely combines global symmetries and Higgs triplets to generate bimaximal mixing and neutrino mass splittings at tree and loop levels, predicting observable lepton flavor violation.

Findings

Bimaximal mixing pattern emerges naturally at tree level.

Neutrino mass splittings are generated at one loop.

Predicts observable $ au o \mu\mu\mu$ decay branching ratios.

Abstract

We present a gauge model for the bimaximal mixing pattern among the neutrinos that explains both the atmospheric and solar neutrino data via large angle vacuum oscillation among the three known neutrinos. The model does not include righthanded neutrinos but additional Higgs triplets which acquire naturally small vev's due to the type II seesaw mechanism. A combination of global $L_e-L_{\mu}-L_{\tau}$ and $S_3$ symmetries constrain the mass matrix for both charged leptons and neutrinos in such a way that the bimaximal pattern emerges naturally at the tree level and needed splittings among neutrinos at the one loop level. This model predicts observable branching ratios for $\tau\to \mu \mu\mu$, which could be used to test it.