Neutrinos, a window on new physics

TL;DR

This paper discusses neutrino physics, focusing on their masses and the potential to determine their Majorana or Dirac nature through Higgs decay measurements at future colliders.

Contribution

It proposes a novel method to test the Majorana nature of neutrinos via Higgs invisible decays, linking collider experiments to neutrino mass mechanisms.

Findings

Majorana neutrinos can be tested through Higgs decay measurements.

The Yukawa couplings influence Higgs invisible decay rates.

Future electron-positron colliders are optimal for such measurements.

Abstract

This paper reviews some aspects of the physics of neutrinos, in particular neutrino masses and the issue of Dirac versus Majorana neutrinos. The see-saw mechanism is described and it is argued that the Majorana nature of neutrinos can be tested by measuring the invisible decays of the Higgs particle, as its decay into neutrinos is determined by their Yukawa couplings, i.e. the Dirac masses, rather than the physical Majorana masses. The measurement would allow us to probe the scale M of the large Majorana masses for right-handed singlet neutrinos. The optimal machine for performing such a measurement would be a future electron-positron collider.