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

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 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

Physics of Electroweak Gauge Boson

The study of gauge bosons is interesting in two respects. The properties of gauge bosons are modified by higher order effects that are sensitive to mass scales not directly accessible to experiment. On the other hand interactions amongst gauge bosons are sensitive to the symmetry structure of the theory where especially the interactions involving longitudinally polarised bosons teach us about the mechanism of electroweak symmetry breaking. This article explains how far a linear collider can increase our knowledge about the properties of and the interactions amongst gauge bosons.Comment: To appear in Linear Collider Physics in the New Millennium. Edited by K. Fujii, D. Miller and A. Soni, World Scientific V2,3: reference adde

b-tagging in DELPHI at LEP

Abstract: The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s=7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb-1 of sqrt(s) = 7 TeV proton-proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results