Lepton-number violating meson decays in theories beyond the Standard Model

TL;DR

This paper explores lepton-number violating meson decays in models beyond the Standard Model, estimating branching ratios and comparing mechanisms within extended theories involving Majorana neutrinos and R-parity violation.

Contribution

It provides new estimates of decay branching ratios and compares different lepton number violation mechanisms in extended Standard Model frameworks.

Findings

Branching ratios estimated for meson decays with lepton number violation.

Comparison of decay mechanisms considering experimental bounds.

Identification of the most effective processes for lepton number violation.

Abstract

After discussion of mechanisms of lepton number violation, we consider meson decays $K^+ \to\pi^ - \ell ^ + \ell '^ +$ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell,\ell ' = e,\mu $) with $\Delta L= 2$ in the Standard Model extended by massive Majorana neutrinos and in a supersymmetric extension of the Standard Model with explicit breaking of R-parity by trilinear or bilinear Yukawa couplings in the superpotential. We give estimates of the branching ratios for these decays and compare the effectiveness of various decay mechanisms taking into account present experimental bounds on lepton mixing, masses of neutrinos and superparticles, and R-parity violating couplings.