Lepton number violating four-body tau lepton decays

TL;DR

This paper investigates lepton number violating four-body tau decays mediated by Majorana neutrinos, proposing that these processes could be enhanced via resonance and serve as sensitive probes for new physics beyond the Standard Model.

Contribution

It introduces a detailed analysis of tau decays involving Majorana neutrinos, highlighting their potential to set stronger constraints on neutrino properties than existing meson decay studies.

Findings

Decay processes can be significantly enhanced via resonance.

Branching fractions sensitivity of 10^-7 can constrain Majorana neutrino parameters.

Proposes these tau decays as promising channels for new physics searches.

Abstract

We study the four-body tau^+- -> nu_tau l^+- l^+- X^-+ decays where l=e or mu and X=pi, K, rho and K^* mesons. These decay processes violate the total lepton number (|Delta L|=2) and can be induced by the exchange of Majorana neutrinos. We consider an scenario where these decays are dominated by the exchange of only one heavy neutrino which produces an enhancement of the decay amplitude via the resonant mechanism. Searches for these novel decay channels with branching fractions sensitivities of (10^-7) can provide constraints on the parameter space of the Majorana neutrinos which are stronger than the ones obtained from Delta L=2 decays of charged pseudoscalar mesons.