Higgsbosonen bortom standardmodellen

Abstract

The Standard Model is the current theory that describes interactions between ele mentary particles. While greatly successful, it does not give a complete description of the universe. Thus, attempts to construct a more complete theory is one of the main driving forces in high-energy physics. In this report, four possible extensions of the physics in the Higgs sector of the Standard Model are studied, namely the scalar singlet model, the composite Higgs model, the two Higgs doublet model, and the Higgs portal dark matter model. In the report, it is investigated how their pa rameters are constrained by experimental data from CERN’s particle accelerator LHC. The investigation is carried out through maximum likelihood estimation of the parameters and Monte Carlo Markov chain analysis. The Bayesian posterior distri butions are presented for the parameter values and show that the Standard Model is still compatible with the results, but for some parameters, the current data al lows deviations from the Standard Model values up to 25 %. The results allow up to 8 % of the Higgs boson to decay to dark matter, which means that a possible coupling strength between dark matter and the Higgs boson is limited to 0.1. The scalar singlet can mix with the Higgs boson up to 18 %. The composite Higgs model can be falsified up to an energy of 1.1 TeV. In the two-Higgs doublet model, a se cond doublet cannot be excluded, and a scenario where the second doublet does not couple to the Standard Model is possible. Overall, the result indicates that the data from LHC is compatible with the Standard Model.