Lepton-number violating four-body decays of heavy mesons

TL;DR

This paper investigates 75 four-body lepton-number violating decays of heavy mesons, providing theoretical calculations of their decay widths and branching ratios, many of which are unexplored experimentally and could reveal Majorana neutrino properties.

Contribution

It introduces the first comprehensive study of four-body LNV decays of heavy mesons, expanding the scope beyond traditional three-body analyses and estimating experimental detectability.

Findings

Most four-body decays have sizable branching ratios.

Branching fractions are comparable to three-body decay modes.

Some channels could be reconstructed with current experimental data.

Abstract

Neutrinoless hadron Lepton Number Violating (LNV) decays can be induced by virtual Majorana neutrino, which in turn indubitably show the Majorana nature of neutrinos. Many three-body LNV processes and Lepton Flavour Violating (LFV) processes have been studied extensively in theory and by experiment. As a supplement, we here study 75 four-body LNV (LFV) processes from heavy pseudoscalar $B$ and $D$ decays. Most of these processes have not been studied in theory and searched for in experiment, while they may have sizable decay rates. Since the four-body decay modes have the same vertexes and mixing parameters with three-body cases, so their branching fractions are comparable with the corresponding three-body decays. We calculate their decay widths and branching fractions with current bounds on heavy Majorana neutrino mixing parameters, and estimate some channels' reconstruction events using the current experimental data from Belle.