Search for a Charged Higgs Boson Produced in the Vector-boson Fusion Mode with Decay $H^\pm \to W^\pm Z$ using $pp$ Collisions at $\sqrt{s}=8$ TeV with the ATLAS Experiment

A search for a charged Higgs boson, $H^\pm$, decaying to a $W^\pm$ boson and a $Z$ boson is presented. The search is based on 20.3 fb$^{-1}$ of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The $H^\pm$ boson is assumed to be produced via vector-boson fusion and the decays $W^\pm \to q\bar{q^\prime}$ and $Z\rightarrow e^+e^-/\mu^+\mu^-$ are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an $H^\pm$ boson is observed. Upper limits of 31-1020 fb at 95% CL are placed on the cross section for vector-boson fusion production of an $H^\pm$ boson times its branching fraction to $W^\pm Z$. The limits are compared with predictions from the Georgi-Machacek Higgs Triplet Model.