Linear Collider Signals of $Z'$ Bosons in GUT Inspired Gauge-Higgs Unification

TL;DR

This paper investigates how $Z'$ bosons predicted by a GUT-inspired gauge-Higgs unification model could be detected at future linear colliders through deviations in fermion pair production, with potential sensitivity up to 15 TeV KK mass scale.

Contribution

It introduces a method to identify $Z'$ signals in GHU models at linear colliders using polarization-dependent observables and estimates the detectable KK mass scale.

Findings

Deviations from the Standard Model can be observed at the ILC with 250 GeV.

Polarization dependence enhances the detection sensitivity of $Z'$ signals.

The KK mass scale can be probed up to about 15 TeV.

Abstract

In gauge-Higgs unification (GHU), the 4D Higgs boson appears as a part of the fifth dimensional component of 5D gauge field. Recently, an $SO(11)$ GUT inspired $SO(5)\times U(1)\times SU(3)$ GHU model has been proposed. In the GHU, Kaluza-Klein (KK) excited states of neutral vector bosons, photon, $Z$ boson and $Z_R$ boson, appear as neutral massive vector bosons $Z'$s. The $Z'$ bosons in the GHU couple to quarks and leptons with large parity violation, which leads to distinctive polarization dependence in, e.g., cross sections and forward-backward asymmetries in $e^-e^+\to\mu^-\mu^+,q\bar{q}$ processes. In the talk, we discuss fermion pair production in $e^-e^+$ linear collider experiments with polarized $e^-$ and $e^+$ beams in the GUT inspired GHU. Deviations from the SM are shown in the early stage of planned international linear collider (ILC) with 250 GeV experiments. The deviations can be tested for the KK mass scale up to about 15 TeV. This talk is mainly based on Phys.Rev.D102(2020)015029.