ATLAS logo

The ATLAS collaboration published the results of searching for the associative production of a Higgs boson and a top–antitop quark pairInvestigations were performed using the data collected in the channels of the Higgs boson decay into \(b\bar b\)WWτ+τγγ and ZZover the entire LHC operation period. The production was observed with the statistical significance of 6.3 standard deviations at the expectation of 5.1 within the Standard Model. It is a pleasure to point out that DLNP scientists take an active part in this analysis, dealing with the channel of the Higgs boson decay into τ+τ.


fig 05 Combined tt̄H production cross section, as well as cross sections measured in the individual analyses, divided by the SM prediction. The γγ and ZZ* → 4ℓ analyses use 13 TeV data corresponding to an integrated luminosity of 79.8 fb-1, and the multilepton and bb̄ analyses use data corresponding to an integrated luminosity of 36.1 fb-1. The black lines show the total uncertainties, and the bands indicate the statistical and systematic uncertainties. The red vertical line indicates the SM cross-section prediction, and the grey band represents the PDF+αSuncertainties and the uncertainties due to missing higher-order corrections. 

tab 03 Measured total tt̄H production cross sections at 13 TeV, as well as observed (Obs.) and expected (Exp.) significances (sign.) relative to the background-only hypothesis. The results of the individual analyses, as well as the combined results are shown. Since no event is observed in the H → ZZ* → 4ℓ decay channel, an observed upper limit is set at 68% confidence level on the tt̄H production cross section in that channel using pseudo-experiments.