Related papers: LEP and radiative electroweak breaking close the l…
The Large Electron-Positron (LEP) collider experiments have constrained the mass of the Standard Model (SM) Higgs boson to be above 114.4 GeV. This bound applies to all extensions of the SM where the coupling of a Higgs boson to the Z boson…
A search for the Standard Model Higgs boson with the OPAL detector at LEP was reported. The analysis was based on the full data sample collected at center-of-mass energies of 192-209 GeV in 1999 and 2000, corresponding to an integrated…
This paper shortly reports on the results of Higgs boson searches performed at LEP and Tevatron. No signal is found and limits on the mass and couplings of the Higgs boson are derived. Interpreting the data in the framework of the Standard…
The LEP era has brought immense progress in searches for Higgs bosons over the last 12 years which will guide searches at future colliders. The evolution of the Higgs boson mass limits are reviewed with the focus on results from general…
The precise measurements of the ``electroweak observables'' performed at LEP and SLC are well consistent with the standard model predictions. Deviations from the standard model arising from vacuum polarization diagrams (also called ``weak…
In a general supersymmetric standard model there is an upper bound $m_h$ on the tree level mass of the $CP=+1$ lightest Higgs boson which depends on the electroweak scale, $\tan \beta$ and the gauge and Yukawa couplings of the theory. When…
In split supersymmetry, gauginos and Higgsinos are the only supersymmetric particles which are possibly accessible at foreseeable colliders. While the direct experimental searches, such as LEP and Tevatron experiments, gave robust lower…
We consider the lightest Higgs boson in naturally R-parity conserving supersymmetric left-right models. We obtain an upper bound on the tree level mass of this lightest Higgs boson. This upper bound depends on the $SU(2)_L$ and $SU(2)_R$…
We examine the current state of neutralino dark matter and consider how the LEP constraints on the Minimal Supersymmetric Standard Model parameters are squeezing the available dark matter regions. We also show how cosmological constraints…
In the Minimal Supersymmetric Standard Model (MSSM) the existence of an upper bound on the mass of the $CP=+1$ lightest Higgs boson, equal to $m_Z$ at tree--level and $\simlt 120\ GeV$ after the inclusion of radiative corrections, has…
We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and scrutinize the property of the Higgs bosons in the allowed parameter space. These constraints come from the precision electroweak data,…
The implications of the LEP Higgs bounds on the MSSM stop masses and mixing are compared in two different regions of the Higgs parameter space. The first region is the Higgs decoupling limit, in which the bound on the mass of the lighter…
The current status of electroweak physics results from LEP is reviewed. Particular emphasis is placed on the latest results on the properties of the Z and W bosons. The updated status of the global electroweak fit to the standard model and…
It is demonstrated that the light Higgs boson scenario, which the lightest Higgs mass is less than the LEP bound, mh > 114.4 GeV, is consistent with the SUSY seesaw model. With the assumptions of the universal right-handed neutrino mass and…
We study the implications of the absence of a direct discovery of a Higgs boson at LEP. First we exhibit 15 physically different ways in which one or more Higgs bosons lighter than the LEP limit could still exist. In the minimal…
The LEP data and the measurement of $M_W$ confirm the electro weak symmetry breaking by the Higgs mechanism with (2--3)\% accuracy. For the Higgs boson mass, fits to the present data (without the SLD result) give $M_h=121^{+207}_{-118}$ GeV…
We study various aspects of $SU(5)\times U(1)$ supergravity as they relate to the experimental verification or falsification of this model. We consider two string-inspired, universal, one-parameter, no-scale soft-supersymmetry-breaking…
When the doubly-charged Higgs bosons $H^{\pm\pm}$ mainly decay into the same-sign dilepton, a lower bound on the mass is around 400 GeV by the current LHC data. On the other hand, no such bound has been reported by using the data at LEP and…
We derive the leptonic neutral current in the simplest little Higgs model and compute the contribution of the model to the decay width $Z \to e^+e^-$. Using the precision electroweak data we obtain a strong lower bound $f\geq 5.6$ TeV at…
Indirect limits on the mass of the lightest neutralino are derived from the results of searches for charginos, neutralinos, and sleptons performed with data taken by the ALEPH Collaboration at centre-of-mass energies near the Z peak and at…