Double-Higgs Production

A major focus in particle physics has been on understanding the interactions of the Higgs boson. Tremendous progress has been made in determining the strength of the couplings of the Higgs boson to fermions and vector bosons, but its self-interaction has yet to be established. Understanding the Higgs self-coupling and the form of the potential function of the Higgs field will illuminate the process by which the Higgs boson acquires a vacuum expectation value and could provide insight into the early Universe and, perhaps, its eventual fate. The most natural way to probe the Higgs self-interaction is via searches for Higgs boson pair ( HH ) production. Since the Standard Model makes a definite prediction for the Higgs self-coupling, enhanced rates and modified kinematic properties of HH production are a smoking-gun signature for new physics. This article reviews the current experimental status of HH searches, discusses the experimental challenges and limitations, and provides an outlook for the future of the field.