Speaker
Description
New massive scalar or pseudo-scalar states with strong couplings to the top quark are predicted in numerous extensions of the Standard Model. These include models with an extended Higgs sector, such as Two-Higgs-Doublet Models (2HDMs). In this talk, two recent searches for new scalar and pseudo-scalar particles with couplings to the top quark using the full LHC Run-2 dataset are presented. Final states with two and four top quarks, targeting production of the heavy Higgs-like states via gluon-gluon fusion (gg→A/H) and associated production with a top-antitop-quark pair (tt̄A/H) are considered. The search in four-top final state is one of the first dedicated searches for tree-level A/H production with t-A/H coupling only. The gg→A/H→tt̄ search takes into account interference with the SM process and provides the first full Run-2 search of this kind at the LHC. The two searches provide complementary coverage in the 2HDM parameter space.
