相关论文: Supersymmetric Hints from Precision Electroweak Da…
The most important hint of physics beyond the Standard Model (SM) from the 1995 precision electroweak data is that the most precisely measured quantities, the total, leptonic and hadronic decay widths of the $Z$ and the effective weak…
Recent LEP results on electroweak precision measurements are reviewed. Line-shape and asymmetries analysis on the Z peak is described. Then, the consistency of the Standard Model predictions with experimental data and consequent limits on…
The predictions of the \sm and the minimal supersymmetric standard model (MSSM) for the electroweak precision parameters are discussed in the light of the recent precision data. The results from global fits yield lower $\chi^2$ values in…
Precision electroweak data allow one to test the standard model, constrain its parameters, and search for the effects of some kinds of new physics. The results of the most recent data from LEP, SLC, and elsewhere are described, as are their…
There are two aspects to the 1995 summer update of the combined preliminary electroweak data from LEP and SLC. On the one hand, agreement between experiments and the Standard Model (SM) has improved for the line-shape and the asymmetry…
The problem of possible deviations from the Standard Model is considered in the framework of a variant of dynamical electroweak symmetry breaking. The parameters of the theory are obtained, which describe deviations from SM in $Z\to \bar b…
These notes contain some of the material I presented at TASI 96 on the comparison of the standard model with precision electroweak data. After a physical accounting of the dominant electroweak radiative corrections, including the effects of…
The Minimal supersymmetric extension of the Standard Model (MSSM) with light stops, charginos or pseudoscalar Higgs bosons has been suggested as an explanation of the too high value of the branching ratio of the Z0 boson into b quarks (Rb…
The 1999 precision electroweak data from LEP and SLC persist in showing some slight discrepancies from the assumed standard model, mostly regarding $b$ and $c$ quarks. We show how their mixing with exotic heavy quarks could result in a more…
We find that re-analyzing the LEP/SLC data with light superpartners and low $\alpha_s(\mz^2)\simeq 0.112$ yields a better fit to the data than the Standard Model, giving a satisfactory description of the $R_b$ measurement, and a better fit…
This is an overview of the electroweak physics achieved at LEP. After a brief review of the standard model and the calculation of the radiative corrections both in the MS and on-shell schemes, we introduce the Z decay parameters around the…
We discuss supersymmetric contributions to the electroweak precision measurements in the Minimal Supersymmetric Standard Model for two cases: the quark-lepton universality violation $\delta_{q\ell}$ in charged currents and the ratio…
We have performed an overall fit to the electroweak data with the generation blind $U(1)$ extension of the Standard Model. As input data for fitting we have included the asymmetry parameters, the particle decay widths of $Z$, neutrino…
We review the available constraints on the low energy supersymmetry. The bulk of the electroweak data is well screened from supersymmetric loop effects, due to the structure of the theory, even with superpartners generically light, ${\cal…
The apparent excess of $Z \rightarrow b \bar b$ events at LEP may be an indication of new physics beyond the standard model. However, in either the two-Higgs-doublet model or the minimal supersymmetric standard model, any explanation would…
A new analysis of the hadronic peak cross section at LEP 1 implies a small amount of missing invisible width in Z decays, while the effective weak charge in atomic parity violation has been determined recently to 0.6% accuracy, indicating a…
A model independent analysis is made using the LEP and SLD data on Z decays available at the end of 1996. The effective weak coupling constants of leptons, c quarks and b quarks are extracted. Except for the right-handed b quark coupling,…
We review the loop effects of the low energy supersymmetry. The global success of the Standard Model rises two related questions: how strongly the mass scales of the superpartners are constrained and can they be, nevertheless, indirectly…
Present data, both from direct Higgs search and from analysis of electroweak data, are starting to become rather restrictive on the possible values for the mass of the standard model Higgs. We discuss a new physics scenario based on a model…
The interpretation of electroweak precision data in the Standard Model Effective Field Theory is discussed. One loop corrections $\propto y_t^2, \lambda$ to the partial $Z$ decay widths and ratios of partial widths in this theory are…