One-loop corrections to the Zb(b)over-bar vertex in models withscalar doublets and singlets

We study the one-loop corrections to the Zb (b) over bar vertex in extensions of the Standard Model with arbitrary numbers of scalar doublets, neutral scalar singlets, and charged scalar singlets. Starting with a general parameterization of theories with neutral and singly-charged scalar particles, we derive the conditions that, in a renormalizable model, must be obeyed by the couplings in order for the divergent contributions to cancel. Then, we show that those conditions are indeed obeyed by the models that we are interested in, and we write down the full finite expression for the vertex in those models. We apply our results to some particular cases, highlighting the importance of the diagrams with neutral scalars. (C) 2020 The Author(s). Published by Elsevier B.V.