An unorthodox alternative for righthanded neutrinos: lefthanded see-saw

TL;DR

This paper introduces a novel lefthanded see-saw mechanism where sterile neutrinos are left-handed, explaining small active neutrino masses without right-handed neutrinos, and involves purely Majorana mass terms.

Contribution

It proposes a new neutrino mass generation mechanism replacing right-handed neutrinos with lefthanded sterile neutrinos, expanding theoretical models of neutrino physics.

Findings

Small active neutrino masses explained by the new mechanism

Heavy sterile neutrinos are decoupled in this model

Neutrino mass terms are purely Majorana types

Abstract

A new lefthanded see-saw mechanism is constructed, implying both the smallness of active-neutrino masses and decoupling of heavy passive neutrinos, similarly to the situation in the case of conventional see-saw. But now, in place of the conventional righthanded neutrinos, the lefthanded sterile neutrinos play the role of heavy passive neutrinos, the righthanded neutrinos and righthanded sterile neutrinos being absent. Here, the lefthanded sterile neutrinos are different from charge conjugates of conventional righthanded neutrinos because their lepton numbers differ. In this case, the neutrino mass term is necessarily of pure Majorana type.