Search for non-resonant di-Higgs production in the bbyy final state at 13 TeV with the ATLAS experiment

The bbγγ channel is one of the most sensitive HH final states for measuring the Higgs self-coupling and di-Higgs production cross-section. This analysis capitalizes on the clean signature of the two photons in the final state combined with the high branching ratio of H→bb. This talk will present the latest non-resonant ATLAS HH→ bbγγ results with the full Run 2 dataset of 139/fb at 13 TeV. The analysis uses a multivariate approach to target high and low HH mass regions to maximize the sensitivity to modifications of the Higgs self-coupling. This result sets the observed (expected) upper limits on the non-resonant HH production cross-section at a 95% confidence level at 130 fb (180 fb), which corresponds to 4.1x (5.5x) the Standard Model value. The analysis provides the strongest observed (expected) limits on the self-coupling of -1.5 to 6.7 (-2.4 to 7.7) to date.