Speaker
Description
We study a search for the charged Higgs boson via $e^+e^− \to H^+H^− \to c\bar b\bar cb$ at the 500 GeV ILC. In a general two Higgs doublet model without $Z_2$ symmetry, extra Yukawa couplings $\rho_{tc}$ and $\rho_{tt}$ can drive electroweak baryogenesis, but searches at the HL-LHC may still go empty-handed if the couplings are relatively weak. Taking $m_{H^+} \simeq m_H \simeq$ $m_A\simeq 200$ GeV, with $\rho_{tc}, \rho_{tt} \sim 0.1$ and no $h(125)$-$H$ mixing, $H^+ \to c\bar b$ decay is dominant, and the $c\bar b\bar cb$ final state is likely overwhelmed by QCD background at the LHC. We show that the electroweak production of $H^+H^−$ at the ILC can be discovered with integrated luminosity of 1 ab$^{−1}$. Furthermore, we show that $m_{H^+}$ can be extracted by requiring the two pairs of $b$ and light jets be roughly equal in mass, without assuming the mass value. Thus, ILC can probe low mass Higgs bosons in multijet final states to complement HL-LHC in the future.
