Electroweak Gauge Theories and Alternative Theories at a Future Linear e+e- Collider

The measurement of Standard Model processes tests the validity of the model at a given scale and is simultaneously sensitive to new physics through loop effects or interference with the Standard Model amplitudes. A variety of studies has been done to see what a linear collider in the energy range MZ < sqrt{s} < 1 TeV can offer. The work that has been done within the ECFA/DESY workshop on linear colliders is reviewed, especially what was not included in the TESLA TDR.Comment: Invited talk presented at the Linear Collider Workshop, Amsterdam, April 200

What is the Case for a Return to the Z-Pole?

The possibilities to run with a linear collider at the Z-pole with high luminosity are examined. Apart from the implications on machine and detector the interest for electroweak and B-physics is discussed.Comment: Plenary talk presented at the LCWS2000 workshop FNA

Electroweak Precision Data and the Higgs Mass - Workshop Summary

The status of the electroweak precision data as of winter 2003 and the corresponding theoretical calculations are presented. The possible problems within the data and the calculations are discussed in a critical way. If the NuTeV anomaly cannot be explained by unknown effects like higher order parton distribution functions and if it is not just a statistical fluctuation the Standard Model of electroweak interactions is in deep problems. Otherwise the conclusions that the Higgs Boson is relatively light seems quite robust within the Standard Model.Comment: Invited talk presented at the Mini-Workshop "Electroweak Precision Data and the Higgs Mass" DESY-Zeuthen, February 28 to March 1 2003 V2: references update

The physics goals of the TESLA project

As next generation e+e- linear collider the superconducting accelerator project TESLA has been proposed. In this note the physics potential goals of this project, which is highly complementary to LHC, are described.Comment: Invited talk presented at the ``Seventh Topical Seminar on The legacy of LEP and SLC'', Siena, October 200

Electroweak and CP violation physics at a Linear Collider Z-factory

A future linear collider such as TESLA may be able to run on the Z0 resonance with very high luminosity and polarised electron and positron beams. The possibilities of measuring electroweak quantities with high precision are investigated. Huge improvements with respect to the present precision can be expected, especially for the asymmetries A_LR and A_b where beam polarisation can be exploited. The very large sample of Z to bbbar events also allows studies of various CP-violating b decays. The precision achievable on the CKM unitarity triangle angles is comparable to experiments at b factories and future hadron colliders.Comment: 26 pages, 11 figures. To be submitted to European Journal of Physics Direc

Experimental studies of Strong Electroweak Symmetry Breaking in gauge boson scattering and three gauge boson production

If no light Higgs boson exist, the interaction among the gauge bosons becomes strong at high energies (~1TeV). The effects of strong electroweak symmetry breaking (SEWSB) could manifest themselves as anomalous couplings before they give rise to new physical states, thus measurement of all couplings and their possible deviation from Standard Model (SM) values could give valuable information for understanding the true nature of symmetry breaking sector. Here we present a detailed study of the measurement of quartic gauge couplings in weak boson scattering processes and a possibility for same measurement in triple weak boson production. Expected limits on the parameters alpha_4 alpha_5,alpha_6, alpha_7 and alpha_10 in electroweak chiral Lagrangian are given.Comment: talk presented at LCWS05, Stanford, USA, March 200