Çetin, Serkant Ali2024-04-262024-04-262023-07-051029-8479https://hdl.handle.net/11411/5333https://doi.org/10.1007/JHEP07(2023)040A search for Higgs boson pair production in events with two b-jets and two tau -leptons is presented, using a proton-proton collision dataset with an integrated luminosity of 139 fb(-1) collected at root s = 13TeV by the ATLAS experiment at the LHC. Higgs boson pairs produced non-resonantly or in the decay of a narrow scalar resonance in the mass range from 251 to 1600 GeV are targeted. Events in which at least one tau-lepton decays hadronically are considered, and multivariate discriminants are used to reject the backgrounds. No significant excess of events above the expected background is observed in the non-resonant search. The largest excess in the resonant search is observed at a resonance mass of 1 TeV, with a local (global) significance of 3.1 sigma (2.0 sigma). Observed (expected) 95% confidence-level upper limits are set on the non-resonant Higgs boson pair-production cross-section at 4.7 (3.9) times the Standard Model prediction, assuming Standard Model kinematics, and on the resonant Higgs boson pair-production cross-section at between 21 and 900 fb (12 and 840 fb), depending on the mass of the narrow scalar resonance.eninfo:eu-repo/semantics/openAccessSTANDARD MODELPLUS PLUSSUPERSYMMETRYSTRAHLUNGPROGRAMPHYSICSLHCNLOArticle2-s2.0-8516447088110.1007/JHEP07(2023)040Q1WOS:001062395700001