# CP Violating Effects in Heavy Neutrino Oscillations: Implications for Colliders and Leptogenesis

## TL;DR

This paper explores how CP violation in heavy neutrino oscillations at TeV-scale colliders can be used to test leptogenesis models, focusing on quasi-degenerate right-handed neutrinos and their observable effects.

## Contribution

It proposes a method to probe CP violating effects and neutrino quasi-degeneracy at colliders using same-sign dilepton charge asymmetry, linking collider signals to leptogenesis viability.

## Key findings

- Identifies parameter regions where leptogenesis can be tested at colliders.
- Confirms a lower bound of about 10 TeV on the $W_R$ mass for successful leptogenesis.
- Proposes collider observables to detect CP violation in heavy neutrino oscillations.

## Abstract

Two of the important implications of the seesaw mechanism are: (i) a simple way to understand the small neutrino masses, and (ii) the origin of matter-anti-matter asymmetry in the universe via the leptogenesis mechanism. For TeV-scale seesaw models, successful leptogenesis requires that the right-handed neutrinos (RHNs) must be quasi-degenerate and if they have CP violating phases, they also contribute to the CP asymmetry. We investigate this in the TeV-scale left-right models for seesaw and point out a way to probe the quasi-degeneracy possibility with CP violating mixings for RHNs in hadron colliders using simple observables constructed out of same-sign dilepton charge asymmetry (SSCA). In particular, we isolate the parameter regions of the model, where the viability of leptogenesis can be tested using the SSCA at the Large Hadron Collider, as well as future 27 TeV and 100 TeV hadron colliders. We also independently confirm an earlier result that there is a generic lower bound on the $W_R$ mass of about 10 TeV for leptogenesis to work.