Combination of di-Higgs searches using 13 TeV data collected by the ATLAS detector

The discovery of the SM Higgs boson in 2012 was a great success of modern particle physics since it served as a proof of the Higgs mechanism introduced in 1964. One focus of the current particle physics experiments at the LHC is the measurement of the Higgs properties, such as its coupling strengths to fundamental particles. In addition to the coupling of the Higgs boson to fermions and gauge bosons, the Higgs mechanism also predicts a coupling to itself. In the SM, there exist 3-Higgs couplings, leading to di-Higgs production. Searches for Higgs boson pair-production are thus a promising way to measure the triple Higgs boson coupling strength. Another important part of di-Higgs analyses is the search for new physics by looking for resonances where a new particle X decays into two Higgs bosons. For these, upper limits on the cross section times branching ratio of the considered processes can be calculated. In addition, the results can be interpreted in various BSM models to determine constraints on the model parameters. By combining di-Higgs searches with different final states like $b\overline{b}b\overline{b}$, $b\overline{b}$$\tau \tau$ and $b\overline{b}$$\gamma \gamma$, the upper limits can be further improved. This talk presents such a combination of different di-Higgs analyses using 36.5 fb${}^{-1}$ of $\sqrt{s}$ = 13 TeV data collected with the ATLAS detector.