In a general two-Higgs-doublet model (2HDM), without the ad hoc discrete symmetries to prevent tree-level flavor-changing-neutral currents, an extra phase angle in the charged-Higgs-fermion coupling is allowed. We show that the charged-Higgs amplitude interferes destructively or constructively with the standard model amplitude depending crucially on this phase angle. The popular model I and II ...

We analyze a composite Higgs model with the minimal content that allows a light Standard-Model-like Higgs boson, potentially just above the current LEP limit. The Higgs boson is a bound state made up of the top quark and a heavy vector-like quark. The model predicts that only one other bound state may be lighter than the electroweak scale, namely a CP-odd neutral scalar. Several other composite...

We study CP violation in a multi-Higgs doublet model based on a S3 × Z3 horizontal symmetry where CKM phase is not the principal source of CP violation. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar Higgs boson mixings. Both mechanisms can explain the observed CP violation in the neutral...

In the global fit of the SM using Gfitter, electroweak precision observables as well as constraints from direct Higgs searches have been compared with state-of-the-art electroweak predictions. We use the most recent results for direct Higgs searches at LEP and Tevatron and the latest measurements of mt and MW . Example results are an estimation of the mass of the Higgs boson (MH = 116.3 +15.6 −...

A program for the calculation of the total Higgs production cross section via gluon fusion at hadron colliders including next–to–leading order QCD corrections is presented. It is suitable especially for Standard Model Higgs bosons and the neutral Higgs particles of the minimal supersymmetric extension. The program provides a model–independent calculation for scalar [CP–even] as well as pseudosc...

We review the constraints on Higgs boson properties from effective potential methods. In the Standard Model, the requirement of stability (or metastability) of the standard electroweak minimum puts an upper bound on the scale of new physics as a function of the Higgs mass. This upper bound is below the Planck scale if the Higgs weights < ∼ 130 GeV. In supersymmetric extensions of the Standard M...

We have adopted two Higgs doublet models to study the production of a Higgs pseudoscalar (A) in association with a Z gauge boson from gluon fusion (gg → ZA) at the CERN Large Hadron Collider. The prospects for the discovery of ZA → ll̄bb̄ are investigated with physics backgrounds and realistic cuts. Promising results are found for mA ∼ 260 GeV in two Higgs doublet models when the heavier Higgs sc...

In the Minimal Supersymmetric Standard Model (MSSM), the minimal extension of the Standard Model (SM), two Higgs doublets are required, resulting in five observable Higgs bosons. Three of them are electrically neutral (h, H , and A) while two of them are charged (H). At tree level their properties like masses, widths and branching fractions can be predicted in terms of only two parameters, typi...

We show that radiative corrections to the Higgs potential in supersymmetric theories with large tan generically lead to large diierences in the light Higgs boson decay branching fractions compared to those of the standard model Higgs boson. In contrast, the light Higgs boson production rates are largely unaaected. We identify W h associated production followed by Higgs boson decays to photons o...

In the minimal Standard Model, it is commonly believed that the Higgs mass cannot be too small, otherwise Top quark dynamics makes the Higgs potential unstable. Although this Higgs mass lower bound is relevant for current phenomenology, we show that the Higgs vacuum instability in fact does not exist and only appears when treating incorrectly the cut-off in the renormalization of a trivial theo...