Searching for a charged Higgs boson with both H±W∓Z and H±tb couplings at the LHC

In certain new physics scenarios, a singly charged Higgs boson can couple to both fermions and W±Z at tree level. We develop new strategies beyond current experimental searches using pp → jjH±, H± → tb at the Large Hadron Collider (LHC). With the effective H±W∓Z and H±tb couplings we perform a model-independent analysis at the collision energy $$ \sqrt{s}=13 $$ TeV with the integrated luminosity of 3 ab−1. We derive the discovery prospects and exclusion limits for the charged Higgs boson in the mass range from 200 GeV to 1 TeV. With |FWZ|, |At| ∼ 0.5–1.0 and 300 GeV ≲ $$ {m}_{H^{\pm }} $$ ≲ 400 GeV, we point out that a discovery significance of 5σ can be achieved. The constraints and projected sensitivities are also discussed in a realistic model, i.e., the modified Georgi-Machacek model without custodial symmetry. Our proposed search would provide direct evidence for a charged Higgs boson H± that couples to W±Z and tb, and has better sensitivity to the couplings of H±W∓Z and H±tb than current searches.