Inverse neutrinoless double beta decay (and other Delta L=2 processes)

TL;DR

This paper reviews the potential for detecting lepton number violating processes at future colliders, highlighting the energy thresholds and constraints from neutrinoless double beta decay on observability.

Contribution

It analyzes the feasibility of observing Delta L=2 processes at future colliders, considering experimental constraints and proposing possible detectable reactions.

Findings

e- e- -> W- W- unobservable unless √s > 2 TeV

mu- mu- -> W- W- could be observed at lower energies

gamma gamma -> mu+ mu+ W- W- may be detectable above 4 TeV

Abstract

I review the prospects for the detection of Delta L=2 processes at future colliders. Except in contrived models, the process e- e- -> W- W- is unobservable at future linear colliders unless $\sqrt{s} \gsim 2$ TeV, due to constraints from neutrinoless double beta decay. As there are no analogous constraints on the Majorana mass of the $\nu_\mu$, mu- mu- -> W- W- could be observed at a muon collider with considerably lower $\sqrt{s}$. One can also consider esoteric processes such as gamma gamma -> mu+ mu+ W- W-. Such processes may be observable if $\sqrt{s} \gsim 4$ TeV.