Search for Higgs boson pair production in association with top-quark pairs using 196 fb−1 of proton–proton collision data at s=13 and 13.6 TeV with the ATLAS detector

This paper presents the first search for non-resonant Higgs boson pair production in association with a top-quark pair (tt¯HH$$ t\overline{t} HH $$) using proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider. The data sample corresponds to an integrated luminos