Search for neutral Higgs bosons within type-I 2HDM at future linear colliders

Abstract

In this study, we investigate observability of the neutral scalar (H) and pseudoscalar (A) Higgs bosons in the framework of the Type-I 2HDM at SM-like scenario at a linear collider operating at √ s = 500 and 1000 GeV. The signal process chain e − e + → AH → ZHH → jjbbbb where jj is a di-jet resulting from the Z boson decay and bb is a b quark pair, is assumed and several benchmark scenarios with different mass hypotheses are studied. The assumed signal process is mainly motivated by the possible enhancements the decay modes A → ZH and H → bb may receive in the Type-I . Event generation is performed for the assumed scenarios separately and the beamstrahlung effects are taken into account. The detector response is simulated based on the SiD detector at the ILC and the simulated events are analyzed to obtain candidate mass distributions of the Higgs bosons. According to the results, the top quark pair production process has the most contribution to the total background and is, however, well-controlled. Results indicate that, in all of the considered scenarios, both of the Higgs bosons H and A are observable with signals exceeding 5σ with possibility of mass measurement. To be specific, at √ s = 500 GeV, the region of parameter space with mH = 150 GeV and 200 ≤ mA ≤ 250 GeV is observable at the integrated luminosity of 500 f b −1 . Also, at √ s = 1000 GeV, the region with 150 ≤ mH ≤ 250 GeV and 200 ≤ mA ≤ 330 GeV with a mass splitting of 50-100 GeV between the H and A Higgs bosons is observable at the same integrated luminosity.

Parameter dependence and analysis of the 2HDM neutral Higgs boson pair production and decay at future lepton colliders

“…At lepton colliders, the 2HDM type 1 has in general lower cross sections compared to other types. We have shown in [40] that signal cross section of about 4f b in 2HDM type 1 (although with slightly different final state from what we propose here) can be observed at √ s = 500 GeV. We have also analyzed the four b-jet final state in 2HDM type 1 at √ s = 1000 GeV in [69] and reasonable results have been obtained for the low mass scenarios.…”

“…In a number of recent works, we analyzed charged [37][38][39] and neutral [40][41][42] Higgs boson production and decay at lepton colliders and provided prospects for their obervation in different scenarios using benchmark points in the parameter space. The above analyses were based on the alignment limit [43][44][45] which is defined as the scenario in which the properties of one of the neutral CP-even Higgs mass eigenstates coincide with those of the SM Higgs boson.…”

Kinematic corrections and reconstruction methods for neutral Higgs boson decay to $b\bar{b}$ in 2HDM type-I at future lepton colliders

“…In type-I, H → b b has been shown to be the most promising decay channel with A → b b [34] or A → ZH with possible leptonic or hadronic decay of the Z boson [35][36][37]. The four b-jet final state through H/A → b b has also shown discovery potential in the flipped type or type-III [38].…”