Speakers
Description
The study of non-resonant Higgs boson pair (HH) production provides direct sensitivity to the Higgs boson self-interaction. This talk presents an ongoing search for non-resonant HH production in multilepton final states using 140fb^-1 of ATLAS Run 2 data and 159fb^-1 of partial Run 3 data collected up to 2024. The analysis combines several complementary final states containing light leptons and hadronically decaying tau leptons. Compared with the previous Run 2 analysis, the strategy incorporates the new Run 3 dataset and introduces new tau channels. Advanced MVA techniques and dedicated background estimation strategies are optimized and developed for the different channels. The combined Run 2 and partial Run 3 analysis is expected to improve the sensitivity by approximately a factor of two compared with the previous Run 2 result, while providing constraints on the coupling modifiers kappa_lambda and kappa_2v.