Charged Higgs decay to $W^{\pm}H$ at a high energy lepton collider

In this work, we present a search strategy for heavy charged Higgs boson at Compact Linear Collider (CLIC) as a future $e^+e^-$ collider. The signal is charged Higgs boson pair production in two Higgs doublet model (2HDM) followed by $H^{\pm}\to W^{\pm}H$ and $H\to b\bar{b}$. Here, $H$ denotes the heavy CP-even neutral Higgs boson of the model. The collider center of mass energy is chosen to be $\sqrt{s}=1400$ GeV as the second stage of CLIC operation. In this case, $m_{H^+}<\sqrt{s}/2$ can be explored due to the pair production. It is shown that the signal of charged Higgs in the mass range 250 GeV $<m_{H^+}<$ 650 GeV in fully hadronic final state, containing four $b$-jets from neutral Higgs and four jets from $W$ bosons, can well be observed on top of the standard model background. Finally 5$\sigma$ contours are presented in ($m_{H^{\pm}}$, $m_H$) space for different $\tan\beta$ values.