CP violation in the semileptonic top decay in two-Higgs doublet model

TL;DR

This paper investigates CP violation in semileptonic top-quark decay within the two-Higgs doublet model, revealing a small but measurable asymmetry influenced by Higgs boson parameters.

Contribution

It provides an exact analysis of CP violation effects in top decay considering multiple Higgs bosons in the two-Higgs doublet model, highlighting the dependence on tan beta.

Findings

CP-violating asymmetry ranges from 1e-4 to 4e-3

Asymmetry is significant for small tan beta values

Results suggest potential observability in future experiments

Abstract

CP violation in semileptonic top-quark decay is investigated by exactly using one charged- and three neutral-Higgs bosons obtained by solving the Higgs mass matrix in two-Higgs doublet model. The CP-violating up-down asymmetry of leptons from $W$ boson decays is shown to be $1 \times 10^{-4} - 4 \times 10^{-3}$ for the region of ${\rm tan} \beta \ll 1$, where ${\rm tan} \beta $ is the ratio of vacuum expectation values for the two neutral Higgs bosons.