Neutrino dark matter candidate in fourth generation scenarios

TL;DR

This paper explores the viability of a heavy fourth-generation neutrino as a dark matter candidate, proposing a new gauge symmetry to address existing constraints and predict observable signatures.

Contribution

It introduces a novel gauge symmetry B-4L_4 that enables the fourth-generation neutrino to serve as a viable cold dark matter candidate, distinct from lighter neutrinos.

Findings

The 4th-generation neutrino must be heavy (> M_Z/2) due to LEP constraints.

The proposed gauge symmetry B-4L_4 differentiates it from lighter neutrinos.

Predictions include specific signals for dark matter detection and collider experiments.

Abstract

We overview the constraints on the 4th-generation neutrino dark matter candidate and investigate a possible way to make it a viable dark matter candidate. Given the LEP constraints tell us that the 4th-generation neutrino has to be rather heavy (> M_Z/2), in sharp contrast to the other three neutrinos, the underlying nature of the 4th-generation neutrino is expected to be different. We suggest that an additional gauge symmetry B-4L_4 distinguishes it from the Standard Model's three lighter neutrinos and this also facilitates promotion of the 4th-generation predominantly right-handed neutrino to a good cold dark matter candidate. It provides distinguishable predictions for the dark matter direct detection and the Large Hadron Collider experiments.