Testing Higgs models via the $H^\pm W^\mp Z$ vertex by a recoil method at the International Linear Collider

TL;DR

This paper investigates the potential to measure the $H^\u00b0 W^\u00b0 Z$ vertex at the ILC, which can reveal the structure of extended Higgs models with higher isospin representations, using a recoil method and analyzing specific decay channels.

Contribution

It proposes a method to measure the $H^\u00b0 W^\u00b0 Z$ vertex at the ILC via single charged Higgs production, providing a way to test extended Higgs models with higher isospin representations.

Findings

The $H^\u00b0 W^ Z$ vertex can be precisely tested for light charged Higgs bosons in the 120-130 GeV range.

Kinematic cuts and polarized beams significantly reduce background events.

The method allows exploration of exotic Higgs sectors through combined vertex and rho parameter analysis.

Abstract

In general, charged Higgs bosons $H^\pm$ appear in non-minimal Higgs models. The $H^\pm W^\mp Z$ vertex is known to be related to the violation of the global symmetry (custodial symmetry) in the Higgs sector. Its magnitude strongly depends on the structure of the exotic Higgs models which contain higher isospin $SU(2)_L$ representations such as triplet Higgs bosons. We study the possibility of measuring the $H^\pm W^\mp Z$ vertex via single charged Higgs boson production associated with the $W^\pm$ boson at the International Linear Collider (ILC) by using the recoil method. The feasibility of the signal $e^+e^-\to H^\pm W^\mp \to \ell \nu jj$ is analyzed assuming the polarized electron and positron beams and the expected detector performance for the resolution of the two-jet system at the ILC. The background events can be reduced to a considerable extent by imposing the kinematic cuts even if we take into account the initial state radiation. For a relatively light charged Higgs boson whose mass $m_{H^\pm}$ is in the region of 120-130 GeV $< m_{H^\pm} < m_W+m_Z$, the $H^\pm W^\mp Z$ vertex would be precisely testable especially when the decay of $H^\pm$ is lepton specific. The exoticness of the extended Higgs sector can be explored by using combined information for this vertex and the rho parameter.