Szczegóły publikacji

The Higgs boson is the last discovered particle of the Standard Model (SM) and the only known fundamental scalar. It crowns the theoretical construction of the SM by providing masses to electroweak bosons through the mechanism of spontaneous symmetry breaking. The essential feature of this mechanism is the famous “Mexican hat” potential with non-zero vacuum expectation value. Measurements of Higgs boson coupling strengths to bosons and fermions, in agreement with SM predictions, have experimentally confirmed the the Brout-Englert-Higgs mechanism of electroweak symmetry breaking. With more data being collected by ATLAS and CMS experiments at the Large Hadron Collider (LHC), more subtle properties of the Higgs boson can be revealed. These measurements will either confirm the SM nature of this particle, leading to a better understanding of the SM, or hint at the existence of beyond Standard Model (BSM) interactions. In this monograph I present results of two sets of studies, that I carried out within the ATLAS experiment, that were aimed at measuring the Higgs potential and searching for beyond Standard Model (BSM) deviations to its shape. One set of analyses uses leptonic Higgs boson decays to W bosons. I measured Higgs boson production cross-sections in gluon fusion and vector boson fusion and constrained Higgs boson couplings to polarised electroweak bosons, thus probing the Higgs potential at its minimum. The other class of measurements focuses on Higgs bosons self-interactions that result from the global shape of the Higgs potential. They are performed by studying the production of the Higgs boson pairs. Due to a very small cross-section for the di-Higgs production predicted by the SM, an observation of this process with the currently available data would hint to the presence of BSM phenomena in the Higgs sector. To maximise sensitivity to Higgs pair production at the LHC, several final states are statistically combined. Results of feasibility studies for the upgraded LHC are also reported, using the b¯bγγ final state. Within experimental uncertainties, a good agreement has been found with the Standard Model and constraints have been set on selected BSM models.