Study of the doubly charged Higgs boson single production using lepton parton distribution functions with the ATLAS detector

Abstract: Searches for the doubly charged Higgs(H±±) aim to find evidence for models that could explain the origin of neutrino masses. Earlier searches at the LHC have used different production processes for the H±±, with the recent development of lepton parton distribution functions new leptonic production processes are able to be studied. In this thesis the single production process l± + l± → H±± has been studied together with its subsequent decay back into charged leptons. The final state of two prompt and isolated same-sign charged leptons is rare at the LHC and is therefore a powerful probe that this thesis will focus on. The triggering, reconstruction and selection of charged leptons at ATLAS Run 2 have been analyzed to give a final estimate of the number of events that could be detected at Run 2, 3 and 4. The final events dependence on model parameters have also been investigated with large differences in cross section. Finally, several improvements to be made for a full analysis is discussed.