Neutrino mass hierarchy and Majorana CP phases within the Higgs triplet model at the LHC

TL;DR

This paper explores how the Higgs triplet model at the LHC can be used to determine the neutrino mass hierarchy and Majorana CP phases through the decay patterns of a doubly charged scalar particle.

Contribution

It demonstrates that decay branching ratios of the doubly charged Higgs triplet can reveal the neutrino mass spectrum and Majorana CP phases at the LHC.

Findings

Decay patterns distinguish neutrino mass hierarchies.

Branching ratios can determine Majorana CP phases.

Potential for direct neutrino mass matrix testing at collider.

Abstract

Neutrino masses may be generated by the VEV of an $SU(2)_L$ Higgs triplet. We assume that the doubly charged component of such a triplet has a mass in the range of several 100 GeV, such that it is accessible at LHC. Its decay into like-sign leptons provides a clean experimental signature, which allows for a direct test of the neutrino mass matrix. By exploring the branching ratios of this decay into leptons of various flavours, we show that within this model the type of the neutrino mass spectrum (normal, inverted or quasi-degenerate) might actually be resolved at the LHC. Furthermore, we show that within the Higgs triplet model for neutrino mass the decays of the doubly charged scalar into like-sign lepton pairs at the LHC provide a possibility to determine the Majorana CP phases of the lepton mixing matrix.