The Quartic Higgs Coupling at Hadron Colliders

The LHC and a future linear collider are widely regarded as an ideal combination of experiments to understand electroweak symmetry breaking, i.e. study the Higgs boson and measure its couplings to all Standard Model bosons and fermions. According to the electroweak precision data [1] we expect to discover and identify a light Standard Model Higgs boson at the LHC [2, 3, 4]. At the ILC we will be able to measure Higgs couplings to all Standard Model particles with great precision [5]. 1 A particularly exciting task is the measurement of the trilinear Higgs self-coupling: for a Standard Model Higgs boson heavier than 150 GeV this coupling can be measured at a luminosity-upgraded LHC (but not at the ILC) [7, 8, 9]. In contrast, for small Higgs masses around 120 GeV it can be measured at the ILC (but possibly not at the LHC) [10, 11, 12].