Distinguishing (Dirac or Majorana) neutrinos in purely leptonic decays of leptons

TL;DR

This paper analyzes purely leptonic decays of leptons to differentiate between Dirac and Majorana neutrinos, finding evidence that favors Dirac neutrinos and proposing extensions to polarization angle studies for further insights.

Contribution

It derives decay width differences between Dirac and Majorana neutrinos considering identical particle effects and suggests new experimental approaches involving lepton polarization angles.

Findings

Evidence strongly favors Dirac neutrinos over Majorana.

Decay width differences can distinguish neutrino types.

Potential for polarization angle analysis to provide additional information.

Abstract

We investigate purely leptonic decays of leptons $\l^{\prime-}\to l^-\bar{\nu}_l\nu_{l^{\prime}}$ to distinguish Dirac or Majorana neutrinos. We derive the differences of the decay width (and associated quantities) between the two neutrino hypotheses by the effect of identical particles. Evidence from experimental data makes the hypothesis of Majorana neutrinos very unlikely and our results strongly favor the hypothesis of Dirac neutrinos (in the standard three-neutrino theory). Moreover, our exploration for decay widths can be extended to the polarization angles of leptons, which will inspire new information for experimental and theoretical studies.