Speaker
Description
We study charged Higgs boson search 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 $\rho_{tt}$ and $\rho_{tc}$ can drive baryogenesis, but
searches at the HL-LHC may still go empty-handed if the couplings are relatively
weak. Taking $m_{H^+} \simeq m_H \simeq m_A \sim 200$ GeV, with $\rho_{tt}$,
$\rho_{tc} \sim 0.1$ 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 is discoverable with integrated luminosity of 1 ab$^{−1}$. We show further
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.
