Dirac-Majorana neutrinos distinction in four-body decays

Abstract

A novel method to differentiate the effects of Dirac and Majorana (D-M) neutrinos in four-body decays has been discussed in arXiv:2106.11785. There, it is concluded that the back-to-back kinematic scenario seems to avoid the constraint imposed by the "practical Dirac-Majorana confusion theorem", as one does not need to fully integrate over neutrino and antineutrino momenta. In this paper, we propose to analyse radiative leptonic lepton-decays ($\ell \to {\ell }^{\prime }\nu \bar{\nu }\gamma$), as an independent alternative process to study the possible Majorana nature of neutrinos. Our approach demonstrates that, in the back-to-back kinematic configuration (for the ${\ell }^{\prime }-\gamma$ and $\nu -\bar{\nu }$ systems, respectively), the distinction between Dirac and Majorana cases disappears when the inaccessible neutrino angle is integrated out, which might appear unexpected considering the claims in arXiv:2106.11785. Our results apply in absence of non-standard interactions, which can enhance generally the sensitivity to the neutrino nature.

30 pages, 7 figures. To match with published version. It replies all points raised in the comments arXiv:2308.08464

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Cited by in corpus (1)

• The Dirac Majorana Confusion Theorem in the Presence of Flavor-Changing Neutral Currents: A CP-Filter Mechanism