Wγ decay of the elusive charged Higgs boson in the two-Higgs-doublet model with vectorlike fermions

摘要

The LHC search for the charged Higgs boson in the intermediate-mass range (M_(H±) ～ m_t) is actively being performed after the next-to-leading order calculation of the total production cross section of pp → H~±W~?bb-bar. In the decay part, only the τν mode is mainly concerned because of the experimental difficulty in the tb mode. In the framework of a two-Higgs-doublet model, we suggest that the W_γ channel can be helpful in probing this charged Higgs boson, if introducing vectorlike fermions. In the type-I-II model where the standard model fermions are assigned in type-I while the vectorlike fermions are in type- II, the branching ratio is greatly enhanced up to ～O(0.01) in a large portion of the parameter space allowed by the Higgs precision data, the electroweak oblique parameters, and the direct search bounds at the LHC. Two kinds of production channels, gg → H~±W~?bb-bar and gg → H=A → H~±W~?, are also studied. We find that the signal rate σ × B(W_γ) is quite sizable, more than 10 fb in some parameter space.