Optimal search reach for heavy neutral leptons at a muon collider

TL;DR

This paper demonstrates that future muon colliders will have the greatest potential to detect heavy neutral leptons in the multi-TeV mass range, surpassing other accelerators in search reach.

Contribution

It provides a comparative analysis of muon and electron colliders' capabilities to search for heavy sterile neutrinos at high energies.

Findings

Muon colliders offer the farthest search reach for heavy neutral leptons above the Z pole.

Comparison shows muon colliders outperform electron colliders of the same energy in this search.

Brief discussion on flavor space complementarity between muon and electron colliders.

Abstract

Neutrinos are the most elusive particles known. Heavier sterile neutrinos mixing with the standard neutrinos might solve the mystery of the baryon asymmetry of the universe. In this letter, we show that among all future energy frontier accelerators, muon colliders will provide the farthest search reach for such neutrinos for mass ranges above the $Z$ pole into the multi-TeV regime. We compare the performance of muon with electron colliders of the same machine energy and briefly discuss the complementarity in flavor space between the two types of accelerators.