Direct CP violation in semi-leptonic and leptonic decays

TL;DR

This paper explores how multi-Higgs doublet models can induce direct CP violation in semi-leptonic and leptonic decays, which are not yet constrained by experimental data due to unmeasured decay branching ratios.

Contribution

It demonstrates the potential for CP violation in these decays within multi-Higgs models and highlights the lack of experimental constraints.

Findings

CP violation can occur in these decays within multi-Higgs models

Current experimental data do not constrain these CP-violating effects

Decays of pions and muons have unmeasured branching ratios

Abstract

We show that direct CP violation in semi-leptonic and leptonic decays can occur in multi-Higgs doublet extensions of the electroweak standard model with flavor changing neutral currents. For pion and lepton decays these $CP$ violating effects cannot be constrained directly by experimental data since up to now the branching ratio of the decays $\pi^-$ and $\mu^-$ have not been measured in laboratory.