Particle Physics Seminar

Abstract: An important parameter of the Standard Model (SM) of particle physics which lacks a precise measurement is the Higgs self-coupling. This parameter is fundamental to the SM and the electroweak symmetry breaking mechanism, as it directly determines the shape of the Higgs potential. A measurement of this parameter serves a dual purpose: It is a crucial test of the SM, and it is a bridge to search for physics Beyond the Standard Model (BSM). The Higgs self-coupling is directly accessible via Higgs pair production (HH), the production of two Higgs bosons. This is a rare process, and requires searches to be performed in final states which are sensitive to detectors and analysis techniques. To this end, HH analyses from the ATLAS experiment often make use of the most common Higgs decay mode: the decay to two bottom quarks. In this seminar, the two most recent HH analyses from the ATLAS experiment using the LHC (Large Hadron Collider) Run 2 dataset will be presented: Higgs pair production in final states including two b-quarks, and either two photons or two light leptons. The two analyses' dedicated strategies will be presented in detail, and their results will be discussed in two contexts: SM interpretations including constraints on the Higgs self-coupling, and BSM interpretations, including the coupling of two vector bosons to two Higgs bosons, and additional Effective Field Theory interpretations.