Associated production of the doubly-charged scalar pair with the Higgs boson in the Georgi–Machacek model at the ILC

Besides the SM-like Higgs boson h  , the Georgi–Machacek (GM) model predicts the existence of doubly-charged Higgs bosons H5±± in the 5-plet representation, which can be seen the typical particles in this model. We first used the latest Higgs boson diphoton signal strength data to find the allowed region at 2σ   confidence level on the plane of the scalar mass values mHmH and the triple scalar coupling parameter ghHHghHH, and then focus on the study of the triple Higgs production process e+e−→hH5++H5−− at the future International Linear collider (ILC). Our numerical results show that, the values of the production cross section are very sensitive to the triple Higgs coupling strength ghHHghHH and can reach the level several fb in the reasonable parameter space. Considering the same-sign diboson decay H5±±→W±W±, the expected discovery reach at the future ILC experiments are also studied.