Same-sign charged Higgs boson pair production in bosonic decay channels at the HL-LHC and HE-LHC

The same-sign charged Higgs pair production via vector-boson scattering is a useful probe of the mass spectrum among the heavier scalar, pseudoscalar, and charged Higgs bosons in two-Higgs-doublet models. It has been shown that the production cross section scales as the square of the mass difference Δm=(mH0-mA0) in the alignment limit (cos(β-α)=0). We study the potential measurement of this same-sign charged Higgs boson pair production at the high-luminosity LHC and the proposed 27 TeV pp collider, with emphasis in the decay channel H±H±→(W±A0)(W±A0), which is in general the dominant mode when the charged Higgs mass is above the W±A0 threshold. We also examine the current allowed parameter space taking into account the theoretical constraints on the model, the electroweak precision test measurements, B decays, and direct searches in the H±→τ±ντ and H±→W±A0→(ℓ±νℓ)(μμ).