Large triple Higgs couplings in the 2HDM at $e^+e^-$ colliders

TL;DR

This paper investigates the potential to measure large triple Higgs couplings in the Two Higgs Doublet Model at future electron-positron colliders, focusing on specific production channels and their sensitivity to these couplings.

Contribution

It identifies benchmark scenarios with large Higgs couplings consistent with constraints and analyzes their detectability at CLIC 3 TeV through di-Higgs production channels.

Findings

Large triple Higgs couplings can be probed at CLIC 3 TeV.

Certain benchmark planes enhance the sensitivity to specific Higgs couplings.

Cross section distributions help distinguish different triple Higgs interactions.

Abstract

Within the framework of the $\cal CP$ conserving Two Higgs Doublet Models (2HDM) type I and II we investigate the di-Higgs production at future $e^+e^-$ colliders in order to find effects coming from triple Higgs couplings. We define and explore some benchmark planes that show large values of these couplings, still in agreement with all the relevant theoretical and experimental constraints. Within those planes two production channels are considered: $e^+e^-\to h_ih_jZ$ and $e^+e^-\to h_ih_j\nu\bar{\nu}$, with $h_ih_j=hh,\ HH\ \mathrm{and}\ AA$. We discuss on the sensitivity to $\kappa_\lambda:=\lambda_{hhh}/\lambda_{hhh}^\mathrm{SM}$ and $\lambda_{hhH}$ in the $hh\nu\bar{\nu}$ production and to $\lambda_{hHH}$ ($\lambda_{hAA}$) in the $HH\nu\bar{\nu}$ ($AA\nu\bar{\nu}$) production at CLIC 3 TeV via the cross section distribution on the invariant mass of the final-state Higgs-pair.