Study of Events with an Electron, Muon, and Two Hadron Jets in the Final State with an Integrated Luminosity of a 139 fb$^{-1}$ in pp Collisions at $\sqrt s $ = 13 TeV with the ATLAS Detector at the LHC

To investigate the Higgs boson properties in the h → WW* → еνμν decay channel, events with an electron, muon, and two hadron jets in the final state recorded with the ATLAS experiment at the LHC are analyzed by the authors as members of the ATLAS Higgs Working Group. The complete statistics of proton–proton collisions at $\sqrt s $= 13 TeV recorded during 2015–2018 exposition is analyzed. Compared to our previous analysis, the statistics was quadrupled, the event-reconstruction procedures and the samples of simulated signal and background events were updated, and special attention was now paid to the events recorded during high-luminosity operation of the LHC. The Monte Carlo simulation is found to satisfactorily describe the measured hadron jet spectra in the signal region in the first stages of initial selection. It is shown that even during high-luminosity operation of the LHC hadron jets emitted at small polar angles are efficiently detected. The kinematic distributions in the control regions of major backgrounds are reasonably reproduced by the MC simulation.