Two-Higgs-doublet type-II and -III models and t → ch at the LHC

We study the constraints of the generic two-Higgs-doublet model (2HDM) type-III and the impacts of the new Yukawa couplings. For comparisons, we revisit the analysis in the 2HDM type-II. To understand the influence of all involving free parameters and to realize their correlations, we employ a chi-square fitting approach by including theoretical and experimental constraints, such as the S, T, and U oblique parameters, the production of standard model Higgs and its decay to gamma gamma, WW*/ZZ*, tau(+)tau(-), etc. The errors of the analysis are taken at 68, 95.5, and 99.7% confidence levels. Due to the new Yukawa couplings being associated with cos(beta - alpha) and sin(beta - alpha), we find that the allowed regions for sin alpha and tan beta in the type-III model can be broader when the dictated parameter chi(F) is positive; however, for negative chi(F), the limits are stricter than those in the type-II model. By using the constrained parameters, we find that the deviation from the SM in h -> Z gamma can be of O(10 %). Additionally, we also study the top-quark flavor-changing processes induced at the tree level in the type-III model and find that when all current experimental data are considered, we get Br(t -> c(h, H)) < 10(-3) for m(h) = 125.36 and m(H) = 150 GeV, and Br(t -> cA) slightly exceeds 10(-3) for m(A) = 130 GeV.