Measuring CP violation in rare $W$ decays at the LHC

TL;DR

This paper explores the potential to detect CP violation in rare W boson decays at the LHC caused by heavy Majorana neutrinos, which could reveal new physics beyond the standard model.

Contribution

It provides a detailed analysis of CP asymmetry in W decays mediated by two Majorana neutrinos, showing it is mass-independent within a specific range, and discusses its experimental detectability.

Findings

CP asymmetry is independent of neutrino mass between 10 and 70 GeV.

Observation of CP asymmetry would indicate physics beyond the standard model.

Rare W decays can serve as probes for Majorana neutrinos and CP violation.

Abstract

Heavy Majorana neutrinos beyond the standard model can simultaneously explain the origin of tiny neutrino masses and matter-antimatter asymmetry in our Universe. The existence of heavy Majorana neutrinos will also lead to lepton number violation and the rare lepton-number-violating $W$ decays are possible. With contributions from two different Majorana neutrinos, a nonzero CP asymmetry may be generated from the rate difference between $W$ decay and its CP-conjugate process. The aim of this paper is to investigate the prospects for measuring CP violation in rare $W$ decays via Majorana neutrinos at the LHC. Our calculations show that the induced CP asymmetry is independent of the Majorana neutrino mass for $10~ \rm GeV < m_N < 70 ~\rm GeV$. Such a CP asymmetry if observed, would in turn provide unambiguous evidence of new physics beyond the standard model.