The impact of additional scalar bosons at the LHC

In this study we consider an effective model by introducing two hypothetical real scalars, H and χ - a dark matter candidate, where the masses of these scalars are 2m_h < m_H < 2m_t and m_χ ≈ m_t /2 with m_h and m_t being the Standard Model Higgs boson and top quark masses, respectively. A distortion in the transverse momentum distributions of h in the intermediate region of the spectrum through the processes pp → H → h_χχ could be observed in this model. An additional scalar, S, has been postulated to explain large H → h_χχ branching ratios, assuming m_h ≲ m_S ≲ m_H - m_h and m_S > 2m_x . Furthermore, a scenario of a two Higgs doublet model (2HDM) is introduced and a detailed proposal at the present energies of the Large Hadron Collider to study the extra CP-even (h, H), CP-odd (A) and charged (H ^±) scalars has been pursued. With possible phenomenological implications, production and decay modes for these scalars are discussed. Based on the mass spectrum of H, A and H ^±, the production of multi-leptons and Z+jets+missing-energy events are predicted. A specific, Type-II 2HDM model is discussed in detail.