Fourth Generation Majorana Neutrinos

TL;DR

This paper explores the theoretical possibility of a fourth Majorana neutrino generation, examining experimental constraints, potential models, and implications for neutrino mass hierarchy within an extradimensional framework.

Contribution

It introduces a novel model for a fourth neutrino generation with Majorana nature, addressing mass hierarchy issues using an extradimensional setup and analyzing experimental constraints.

Findings

Constraints from neutrinoless double beta decay are considered.

Potential signals at hadron colliders are discussed.

A new mass model softens neutrino mass hierarchy issues.

Abstract

We investigate the possibility of a fourth sequential generation in the lepton sector. Assuming neutrinos to be Majorana particles and starting from a recent - albeit weak - evidence for a non-zero admixture of a fourth generation neutrino from fits to weak lepton and meson decays we discuss constraints from neutrinoless double beta decay, radiative lepton decay and like-sign dilepton production at hadron colliders. Also an idea for fourth generation neutrino mass model building is briefly outlined. Here we soften the large hierarchy of the neutrino masses within an extradimensional model that locates each generation on different lepton number violating branes without large hierarchies.