Possibility of observing Higgs bosons at the ILC in the lepton-specific 2HDM

TL;DR

This paper investigates the potential to observe Higgs boson pairs in the lepton-specific 2HDM at the ILC, demonstrating that significant signals could be detected with current or near-future collider capabilities.

Contribution

It provides a detailed analysis of Higgs pair production in the lepton-specific 2HDM at the ILC, including simulation results and benchmark scenarios for different energies and luminosities.

Findings

Significant Higgs pair signals are detectable beyond LHC reach.

Main background processes are well controlled.

Lower luminosities suffice for discovery than previously thought.

Abstract

The Higgs boson pair production at a linear $e^+e^-$ collider is analyzed in the $4\tau$ final state in the context of lepton-specific or type IV 2HDMs. Both beams are assumed to be unpolarized. The Higgs boson pairs (HA) are produced through off-shell $Z^*$ production and decay to $\tau$-jets which is the main decay channel for neutral Higgs bosons in type IV. Using a simplified detector simulation based on SiD detector at ILC, the 4$\tau$ signal is studied through the $\tau$-jet pair invariant mass reconstruction. Several benchmark scenarios are considered for center of mass energies of 500 and 1000 GeV at integrated luminosity of 500$fb^{-1}$. Among Standard Model (SM) background processes, the main background is $e^+e^- \to ZZ$ followed by $Z \to \tau\tau$. This background is however, well under control. With the luminosity assumed in the analysis, striking signals are obtained beyond the reach of LHC. Such signals would allow for precise determination of masses and cross sections and alredy much lower luminosities are sufficient for discovery.