Search for non-resonant HH production in the $b\bar{b}\gamma\gamma$ final state : Higgs self-coupling constraints

Since the Higgs boson discovery in 2012, measuring its properties and couplings with high precision is a priority for ATLAS and CMS. The Higgs coupling to itself is providing a direct probe on the EWSB and is a precision test of the electroweak theory but has not been observed yet. Measuring the total and differential ($m_{HH}$) cross-sections of two Higgs boson production is the current way to probe the trilinear coupling component. The low cross-section (31 fb at 13 TeV) at SM requires large integrated luminosity. But new physics might enhance non-resonant HH production by modifying the Higgs self-coupling. This poster focuses on the attempt to observe di-Higgs production through the decay of one $H\to b\bar{b}$ (largest branching ratio) and the other one $H\to \gamma\gamma$ benefiting from its excellent di-photon resolution to maximize background rejection. The $\bar{b}\gamma\gamma$ final state is one of the most promising decay channel. The poster will present the recent analysis developments to maximize the statistical power of the dataset which includes the overall Run-2 data (139 fb$^{-1}$) collected by the ATLAS detector. The upper limit on the cross-section and the measurement of of the Higgs self coupling parameter will be presented.