Constraints on Off-shell Higgs Boson Production and the Higgs Boson Total Width in ZZ Final states with the ATLAS Detector

The off-shell production of SM Higgs boson, at the high-mass off-peak region beyond 2$m_{Z}$, well above the measured resonance mass of $m_{H}$=125 GeV, has a substantial cross section at the LHC, due to the increased phase space as the Z bosons become on-shell with the increasing energy scale. This presents a novel way of characterizing the properties of the Higgs boson in terms of the off-shell event yields, normalized to the SM prediction (referred to as signal strength μ), and the associated off-shell Higgs boson couplings. Assuming the ratio of the Higgs boson couplings to the SM predictions is independent of the momentum transfer of the Higgs boson production mechanism, a combination with the on-shell signal- strength measurement was used to set indirect limits on the total Higgs boson width with the 36 fb$^{-1}$ ATLAS Run-2 data collected in proton-proton collisions at the centre-of-mass energy of $\sqrt{s}$ = 13 TeV.