Simulating lepton number violation induced by heavy neutrino-antineutrino oscillations at colliders

TL;DR

This paper investigates how heavy sterile neutrinos that oscillate between neutrino and antineutrino states can lead to lepton number violation at colliders, using a minimal low-scale seesaw model and simulation tools.

Contribution

It introduces a minimal phenomenological framework for low-scale seesaws, implements it in FeynRules, and extends MadGraph to simulate neutrino-antineutrino oscillations at colliders.

Findings

Simulation of heavy neutrino-antineutrino oscillations at colliders.

Demonstration of lepton number violation signals.

Implementation of a minimal model in Monte Carlo tools.

Abstract

We study pseudo-Dirac pairs of two almost mass-degenerate sterile Majorana neutrinos which generate light neutrino masses via a low-scale seesaw mechanism. These pseudo-Dirac heavy neutral leptons can oscillate between interaction eigenstates that couple to leptons and antileptons and thus generate oscillations between lepton number conserving and lepton number violating processes. With the phenomenological symmetry protected seesaw scenario (pSPSS), we introduce a minimal framework capable of describing the dominant features of low-scale seesaws at colliders and present a FeynRules implementation usable in Monte Carlo generators. Additionally, we extend MadGraph to simulate heavy neutrino-antineutrino oscillations and present results from such simulations.