ILC Phenomenology of the $Z_3$ symmetric Type-Z Three Higgs Doublet Model

TL;DR

This paper explores the phenomenology of a $Z_3$ symmetric three-Higgs-doublet model at the future ILC, identifying promising channels for discovering new Higgs bosons beyond the Standard Model.

Contribution

It provides a detailed analysis of the extended Higgs sector in the 3HDM and highlights key production channels at the ILC for probing this new physics.

Findings

Certain production channels have large cross-sections suitable for detection.

The ILC can effectively test the extended Higgs sector predictions.

Potential to discover heavier Higgs bosons beyond the Standard Model.

Abstract

The Three-Higgs-Doublet Model (3HDM) extends the Standard Model by introducing two additional scalar doublets, leading to a rich spectrum of new particles: three neutral CP-even Higgs bosons ($h_1$, $H_2$, $H_3$), two neutral CP-odd Higgs bosons ($A_2$, $A_3$), and two charged Higgs bosons ($H_2^+$, $H_3^+$). In this work, we present a phenomenological study of the 3HDM at the future International Linear Collider (ILC) with a center-of-mass energy of $\sqrt{s} = 1000\,\text{GeV}$. Applying a comprehensive set of theoretical and experimental constraints, we identify promising new physics signals with sufficiently large production cross-sections. Our analysis shows that $e^+e^- \to H_2 A_2$, $e^+e^- \to H_2 H_2 Z$, $A_2 A_2 Z$, $H_2 H_2^{\pm} W^{\mp}$, $A_2 H_2^{\pm} W^{\mp}$ and $H_1 H_2 A_2$ are among the most sensitive channels to probe this extended Higgs sector. We demonstrate that a future ILC would offer a powerful platform to test these interactions and discover these heavier Higgs bosons thus providing evidence of physics beyond the Standard Model.