Goussiou, AnnaSales de Bruin, Pedro Henrique2016-09-222016-09-222016-09-222016-08SalesdeBruin_washington_0250E_16415.pdfhttp://hdl.handle.net/1773/37219Thesis (Ph.D.)--University of Washington, 2016-08The searches for a Beyond Standard Model (BSM) heavy CP-odd Higgs boson $A$ decaying to $Zh$ in the context of two-Higgs-doublet models (2HDM), and Minimal Supersymmetric Standard Model (MSSM) neutral Higgs bosons $H/A$ decaying to a tau pair are presented. The search for the heavy CP-odd Higgs boson, $A$, is conducted through the $A\rightarrow Zh\rightarrow \ell\ell\lephad$ decay channel using 20.3 \ifb\ of proton-proton collision data collected by the ATLAS detector at a center-of-mass of 8 TeV. The search for the neutral MSSM $H/A$ decaying to a tau pair in the $\lephad$ $b$-veto final state is done using 3.2 \ifb\ of proton-proton collision data recorded by the ATLAS detector at a center-of-mass of 13 TeV. The observed data agrees with the Standard Model background prediction, and upper limits are set on cross-section times branching ratio of neutral BSM Higgs bosons.application/pdfen-US2HDMBSMHiggsLHCMSSMParticle physicsPhysicsphysicsThesis