Extra Neutral Scalars With Vectorlike Fermions At The Lhc

Many theories beyond the standard model (BSM) contain new CP-odd and CP-even neutral scalars phi = {A, H}, and new vectorlike fermions (psi(VL)). The couplings of the CP-odd scalar A to two standard model (SM) gauge bosons cannot occur from renormalizable operators in a CP-conserving sector, but can be induced at the quantum loop level. We compute these effective couplings at the 1-loop level induced by the SM fermions and vectorlike fermions, present analytical expressions for them, and plot them numerically. Using the 8 TeV Large Hadron Collider (LHC) gamma gamma, tau(+)tau(-) and t (t) over bar channel data, we derive constraints on the effective couplings of the phi to standard model gauge bosons and fermions. We present the gluon-fusion channel cross sections of the phi at the 8 and 14 TeV LHC, and its branching ratios into SM fermion and gauge-boson pairs. We first present our results in a model independent manner, and then we provide results for some simple models containing phi and psi(VL) in the singlet and doublet representations of SU(2). In the doublet case, we focus on the two-Higgs-doublet (2HDM) Type-II and Type-X models in the alignment limit.