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

In this paper, an approach for neutral Higgs bosons search is described based on 2HDM type-I at electron-positron linear colliders operating at $\sqrt{s}=1$ TeV. The beam is assumed to be unpolarized and fast detector simulation is included. The signal process produces a fully hadronic final state through $e^{+}{e}^{-}\to AH\to b\bar{b}b\bar{b}$ where both CP-even and CP-odd Higgs bosons ($H$ and $A$) are assumed to decay to a pair of $b$-jets. Several benchmark scenarios are introduced as the baseline for the analysis taking $m_{H\mathrm{/}A}$ in the range 150–300 GeV. In order to avoid Higgs boson conversion $A\to ZH$, Higgs boson masses are chosen with $m_A-m_H<m_Z$. It is shown that with a proper kinematic correction applied on final state $b$-jet four momenta, true combinations of $b$-jets can be found for simultaneous reconstruction of both Higgs bosons through $b\bar{b}$ invariant mass calculation. Results show that observable signals can be achieved with statistical significance exceeding $5\sigma$ well before the target integrated luminosity of 8 $a{b}^{-1}$.