[eng] The Brout-Englert-Higgs mechanism proposed in the 60's predicts the existence of the Higgs boson, the last undiscovered elementary particle of the Standard Model of fundamental interactions. It is based on the presence of one doublet field governing the scalar potential of the theory. Alternative models predict more scalar doublet fields and a corresponding increase of the number of Higgs particles. The observation of these Higgs bosons is one of the primary goals of the Large Hadron Collider, whose first collisions are expected in 2010. In this context, particular attention is given in this work on the quality of hadron collision modeling. This includes multi-jet final states which are particularly dangerous backgrounds to many searches at the LHC as well as heavy colored particle production which could be the sign of new physics.
In this thesis an unconventional realization of the two-Higgs-doublet model is presented, which is mainly characterized by an inverted mass hierarchy of the resulting Higgs particles. It is shown that this model cannot be excluded by existing theoretical and experimental constraints and that it could be observed at the LHC via a large variety of experimental signatures in CMS and ATLAS detectors.
In particular, it is shown that the pseudo scalar Higgs particle, the A boson, could be discovered in CMS only after a few inverse femptobarns of integrated luminosity via the production of another Higgs particle decaying into Z and A bosons which subsequently decay into charged leptons.