Weekly Seminar: (Spooky) Higgs pair production searches at the LHC

by Agni Bethani (CERN - EP/UAT)

Thursday 31 Oct 2019, 13:00 → 15:00 Europe/Brussels

Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve)

The Higgs boson was discovered by the ATLAS and CMS Collaborations in 2012, at the LHC, at CERN. This was the last missing piece of the Standard Model (SM) of particle physics as we know it today. At the LHC, we have measured the mass of the Higgs boson (125 GeV), and it is couplings to other particles. So far, all measurements are compatible with the SM predictions. However, the Higgs potential is the least explored part of the SM. In order to experimentally determine the shape of the Higgs field potential, we need to measure the Higgs self-coupling, a parameter that determines how the Higgs boson interacts with itself. To access the Higgs trilinear self-coupling, we can study the production of Higgs pairs (HH) at the LHC.  Determining the shape of the Higgs potential will have consequences for particle physics and cosmology. The HH production is an excellent handle for searching for new physics. The observed HH cross section can be altered with respect to the SM expectation by modifications of the Higgs self-coupling λ, Higgs couplings to other particles or by introducing production mechanisms with new intermediate particles. Theories beyond the SM (BSM) predict heavy particles that could decay to a pair of SM Higgs bosons. The ATLAS and CMS collaborations have studied the HH pair production in data recorded in 2015-2018 at the LHC and have also published projections for HL-LHC.