Search for a heavy scalar boson decaying into a pair of Standard-Model-like Higgs bosons, in the final state $b \overline b \tau^+ \tau^-$ with both $\tau$ decaying hadronically, at CMS experiment

This thesis presents the search for a heavy scalar boson H, decaying in two Standard Model like Higgs bosons h with a mass around 125 GeV. The final state consists of a pair of b jets and a pair of τ, where both τ leptons decay into hadrons plus a tau neutrino. The search uses proton-proton collisions data collected by the Compact Muon Solenoid (CMS) experiment during 2012, at a centre of mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1. The results have shown no evidence for a heavy boson H and are compatible with the Standard Model expectations. Upper limits are set at 95% confidence level on the production cross–section times the branching fraction of the heavy boson H, in the final state hh→bbττ, for a H mass in the range 260≤MH ≤350GeV. The results are also interpreted in the context of benchmark scenarios of the Minimal Supersymmetric Extension of the Standard Model (MSSM) and of the Two- Higgs-Doublet Model (2HDM). Exclusion limits are set in the two dimensional parameter space of these two models.