In the Standard Model, the Higgs boson self-coupling strength is related to the quartic term in the energy potential of the Higgs field, which is responsible for electroweak symmetry breaking. The self-coupling can be studied experimentally through the production of pairs of Higgs bosons (HH). This seminar reports new HH searches and their combination, obtained by ATLAS with the full LHC Run 2 proton–proton dataset at 13 TeV.
The new results include: improved HH→bbγγ and HH→bbττ, the addition of boosted VBF HH→bbbb, and new final states HH→bb+ℓℓ+MET,  HH→multi-lepton, and HH→γγ+multi-lepton.
Combined constraints on the HH production cross section, the Higgs boson self-coupling strength, and the HHVV (V = W or Z boson) coupling strength are derived. The results are further interpreted in the context of effective field theories. Extrapolations of recent ATLAS HH results for the High-Luminosity LHC are also discussed.

Refreshments will be served at 10:30