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 sqrt{s}= 500 and 1000 GeV. The signal process is e^- e^+ rightarrow A H rightarrow ZHHrightarrow jj b{bar{b}}b{bar{b}} where jj is a di-jet resulting from the Z boson decay and b{bar{b}} is a b-jet pair from scalar Higgs boson decay. Several benchmark scenarios with different mass hypotheses are studied. The assumed signal process is mainly motivated by the large decay rate of Arightarrow ZH (at high tan beta and enough Higgs boson mass splitting) and Hrightarrow b{bar{b}} in the type-I. After event generation the detector response is simulated based on the SiD detector at the ILC. The ISR and beamstrahlung effects are also included for each center of mass energy assuming unpolarized beams. The simulated events are analyzed to obtain candidate mass distributions of the Higgs bosons. Among standard model backgrounds, the top quark pair production process is the main background but is under control. Results indicate that, in all considered scenarios, both Higgs bosons H and A are observable with signals exceeding 5sigma with possibility of mass measurement. Final results are shown as 5sigma contours in (m_H,m_A) or (m_A,tan beta ) space.