Updated projections for Higgs boson measurements using H→γγ, Zγ and μμ decays and for the combined measurement of Higgs boson couplings with the ATLAS detector at the HL-LHC

Updated estimates are presented of the expected precision for the Higgs boson measurements in the H→γγ, Zγ and μμ final states with the ATLAS detector at the High Luminosity LHC. The measurements performed in the same final states using the full ATLAS Run 2 data are projected to integrated luminosities ranging from 1000 fb⁻¹ to 3000 fb⁻¹, at a centre-of-mass energy of 14 TeV. They are obtained in baseline, optimistic and conservative scenarios of systematic uncertainties. In addition, the latest ATLAS extrapolations of single Higgs-boson measurements in the baseline uncertainty scenario with 3000 fb⁻¹ are used in a joint interpretation to derive the expected uncertainties in the scale factors of various Higgs boson coupling strengths.