Probing the Seesaw Mechanism and Leptogenesis with the International Linear Collider

TL;DR

This paper explores how the International Linear Collider can detect heavy sterile neutrinos and measure their properties to test the seesaw mechanism and leptogenesis, linking neutrino physics with the universe's matter-antimatter asymmetry.

Contribution

It demonstrates the ILC's potential to discover sterile neutrinos and measure active-sterile mixing angles, providing a way to test minimal seesaw models and leptogenesis.

Findings

Heavy sterile neutrinos can be detected via displaced vertices at ILC.

Precision measurements of mixing angles can test the seesaw model.

ILC can serve as a discovery platform for new physics related to neutrino mass and cosmology.

Abstract

We investigate the potential of the International Linear Collider (ILC) to probe the mechanisms of neutrino mass generation and leptogenesis within the minimal seesaw model. Our results can also be used as an estimate for the potential of a Compact Linear Collider (CLIC). We find that heavy sterile neutrinos that simultaneously explain both, the observed light neutrino oscillations and the baryon asymmetry of the universe, can be found in displaced vertex searches at ILC. We further study the precision at which the flavour-dependent active-sterile mixing angles can be measured. The measurement of the ratios of these mixing angles, and potentially also of the heavy neutrino mass splitting, can test whether minimal type I seesaw models are the origin of the light neutrino masses, and it can be a first step towards probing leptogenesis as the mechanism of baryogenesis. Our results show that the ILC can be used as a discovery machine for New Physics in feebly coupled sectors that can address fundamental questions in particle physics and cosmology.