Discovering sterile Neutrinos ligther than $M_W$ at the LHC

TL;DR

This paper explores how to detect sterile neutrinos lighter than the W boson at the LHC by analyzing specific leptonic W decays, aiming to determine their Dirac or Majorana nature through muon spectrum analysis.

Contribution

It introduces a method to distinguish Dirac from Majorana sterile neutrinos at the LHC via leptonic W decay channels and muon spectrum analysis.

Findings

Potential to identify sterile neutrino nature at the LHC

Distinct muon spectrum signatures for Dirac and Majorana neutrinos

Feasibility of detection even with undetected neutrinos

Abstract

We study the purely leptonic $W$ decays $W^+ \to e^+ \mu^- e^+ \nu_e$ and $W^+ \to e^+ e^+ \mu^- \bar \nu_\mu$ (or their charge conjugates) produced at the LHC, induced by sterile neutrinos with mass below $M_W$ in the intermediate state. While the first mode is induced by both Dirac or Majorana neutrinos, the second mode is induced only by Majorana neutrinos, as it violates lepton number. We find that, even when the final (anti-)neutrino goes undetected, one could distinguish between these two processes, thus distinguishing the Dirac or Majorana character of the sterile neutrinos, by studying the muon spectrum in the decays.