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

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 two Higgs doublet models (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 2HDM type IV. Using a simplified detector simulation based on the 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 background processes, the main background is e(+)e(-) -> ZZ followed by Z -> tau tau. This background is, however, well under control. With the luminosity assumed in the analysis, striking signals are obtained beyond the reach of the LHC. Such signals would allow for precise determination of masses and cross sections and already much lower luminosities are sufficient for discovery.