These final results from DELPHI searches for the Standard Model SM Higgs boson, together with benchmark scans of the Minimal Supersymmetric Standard Model MSSM neutral Higgs bosons, used data taken at centre-of-mass energies between 200 and 209 GeV with a total integrated luminosity of 224 pb−1.The data from 192 to 202 GeV are reanalyzed with improved b-tagging for MSSM final states decaying to...

We have used detailed Monte Carlo simulations to study search strategies for Higgs bosom at high energy e+ecolliders. We extend an earlier study of the minimal single-Higgs-doublet model at a center-of-mass energy of 1 TeV to examine the effects of b-quark tagging and jet counting. It is found that these techniques can increase the signal-to-noise ratio substantially in the mass range around th...

A Higgs boson with mass below 150 GeV has a total decay width of less than 20 MeV into accessible Standard Model states. This narrow width means that the usual branching fractions for such a light Higgs boson are highly susceptible to any new particles to which it has unsuppressed couplings. In particular, there are many reasonable and interesting theoretical ideas that naturally imply an invis...

We construct effective 3d field theories for the Minimal Supersymmetric Standard Model, relevant for the thermodynamics of the cosmological electroweak phase transition. The effective theories include a 3d theory for the bosonic sector of the original 4d theory; a 3d two Higgs doublet model; and a 3d SU(2)+Higgs model. The inte-grations are made at 1-loop level. In integrals related to vacuum r...

Nobody knows exactly what kind of Higgs physics will be unveiled when the Large Hadron Collider is turned on. There could be one Standard Model Higgs boson or five Higgs bosons as is the case in two-Higgs-doublet models; there could be more exotic or even completely unexpected scenarios. In order to be prepared for the LHC era, a solid understanding of Standard Model or Standard-Model-like Higg...

We analyse the consequences of the little Higgs model for double Higgs boson production at the LHC and for the partial decay width Γ(H → γγ). In particular, we study the sensitivity of these processes in terms of the parameters of the model. We find that a generic prediction is that the partial width Γ(H → γγ) is greatly suppressed with respect to the standard model due to a cancellation betwee...

In models with a non-minimal Higgs sector, the lightest scalar state may be a neutral CP-even Higgs boson, whose properties are nearly identical to those of the minimal Higgs boson of the Standard Model. In such a scenario, the other Higgs scalars are significantly heavier than mZ ; their effects rapidly decouple from the low-energy theory. The decoupling limit of the most general CP-conserving...

A short review of the theory and phenomenology of Higgs bosons is given, with focus on the Standard Model (SM) and the minimal supersymmetric extension of the Standard Model (MSSM). The potential for Higgs boson discovery at the Tevatron and LHC, and precision Higgs studies at the LHC and a future e+e− linear collider are briefly surveyed. The phenomenological challenge of the approach to the d...