Searching for a charged Higgs boson with both $H^{\pm }{W}^{\mp }Z$ and $H^{\pm }tb$ couplings at the LHC

Abstract

In certain new physics scenarios, a singly charged Higgs boson can couple to both fermions and $W^{\pm }Z$ at tree level. We develop new strategies beyond current experimental searches using $pp\to jj{H}^{\pm }$, $H^{\pm }\to tb$ at the Large Hadron Collider (LHC). With the effective $H^{\pm }{W}^{\mp }Z$ and $H^{\pm }tb$ couplings we perform a model-independent analysis at the collision energy $\sqrt{s}=13$~TeV with the integrated luminosity of $3{\text{ab}}^{-1}$. We derive the discovery prospects and exclusion limits for the charged Higgs boson in the mass range from 200~GeV to 1~TeV. With $|F_{WZ}|,|A_t|\sim 0.5-1.0$ and $300\text{GeV}\lesssim m_{H^{\pm }}\lesssim 400\text{GeV}$, we point out that a discovery significance of $5\sigma$ 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 $H^{\pm }$ that couples to $W^{\pm }Z$ and $tb$, which can have better sensitivity to the couplings of $H^{\pm }{W}^{\mp }Z$ and $H^{\pm }tb$ than current searches.

Comments: match the published version in JHEP