Speaker
Description
A new search is presented for the production of a doubly charged Higgs boson via vector-boson fusion (VBF) with the ATLAS detector at the Large Hadron Collider. The doubly charged Higgs decays into same-sign W boson pairs, where only fully leptonic (electrons and muons) decays of the W bosons are considered. Events are required to contain two forward jets, two same-sign leptons, and missing energy. This search utilizes the full proton-proton collision dataset collected during Run 2 at center-of-mass energy 13 TeV and a partial dataset collected during Run 3 in 2022-2023 at center-of-mass energy 13.6 TeV. These correspond to integrated luminosities of 140 fb^−1 and 56.3 fb^−1, respectively. The search follows up on a Run 2 search that had an intriguing excess around 450 GeV. Both a selection-based and a boosted decision tree analysis approach are described, with each optimized to provide enhanced sensitivity over the parameter space of the Georgi-Machacek (GM) model. Results are interpreted in the context of the GM model