Design and Construction of a TPC using GEM Foils for Gas Amplification

The challenging physics program at the International Linear Collider (ILC) poses stringent requirements on the performance of its tracking system. A large volume time projection chamber (TPC) is considered a good candidate for such a tracker. Whereas conventional TPCs used a wired based gas amplification system, a future TPC is likely to make use of micro pattern gas detectors as e. g. gas electron multipliers (GEMs) for gas amplification. This talk gives an overview over recent achievements from the R&D activities to build a TPC with a GEM based gas amplification system. This includes charge transfer studies through multiple GEM structures, field cage design and spatial resolution measurements in high magnetic fields.Comment: 4 pages, 4 figures, to be published in the proceedings of the 32nd International Conference on High Energy Physics 2004 (ICHEP04

Exclusive SUSY measurements and determination of Lagrangian parameters from LHC data

This talk gives an overview over exclusive SUSY measurements which are possible with early Atlas data and describes how these data can be used to infer theory parameters from these measurements

Extracting SUSY parameters from LHC measurements using Fittino

We show that presently available precision data are in good agreement with supersymmetry at a mass scale below 1 TeV. Using a SUSY point close to the best fit to present data, we give a projection of the capabilities of the LHC to constrain SUSY models and their parameters as function of the accumulated luminosity.Comment: 4 pages, contribution to the proceedings of the 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY09), Northeastern University, Boston, MA, USA, June 200

Exclusive SUSY measurements and determination of SUSY parameters from LHC data

A selection of exclusive SUSY measurements is presented which can be performed provided SUSY will be discovered at the LHC. Such measurements allow to determine the properties of supersymmetry and thus help to pin down the underlying theoretical model. It is described on an mSUGRA example point how sparticle masses can be reconstructed from endpoints in mass spectra using early LHC data. Finally it is shown how well mSUGRA model parameters can be derived from these measurements.Comment: 3 pages, contribution to the proceedings of the 16th International Conference on Supersymmetry and the Unification of Fundamental Interactions, June 16 - 21, 2008, Seoul, Kore

Supersymmetry Parameter Analysis with Fittino

We present the results of a realistic global fit of the Lagrangian parameters of the Minimal Supersymmetric Standard Model to simulated data from ILC and LHC with realistic estimates of the observable uncertainties. Higher order radiative corrections are accounted for where ever possible to date. Results are obtained for a modified SPS1a MSSM benchmark scenario but they were checked not to depend critically on this assumption. Exploiting a simulated annealing algorithm, a stable result is obtained without any a priori assumptions on the fit parameters. Most of the Lagrangian parameters can be extracted at the percent level or better if theoretical uncertainties are neglected. Neither LHC nor ILC measurements alone will be sufficient to obtain a stable result. The effects of theoretical uncertainties arising from unknown higher-order corrections and parametric uncertainties are examined qualitatively. They appear to be relevant and the result motivates further precision calculations.Comment: 6 pages, 2 figures, presented at the Linear Collider Workshop 2005, Stanfor

Killing the cMSSM softly

We investigate the constrained Minimal Supersymmetric Standard Model (cMSSM) in the light of constraining experimental and observational data from precision measurements, astrophysics, direct supersymmetry searches at the LHC and measurements of the properties of the Higgs boson, by means of a global fit using the program Fittino. As in previous studies, we find rather poor agreement of the best fit point with the global data. We also investigate the stability of the electro-weak vacuum in the preferred region of parameter space around the best fit point. We find that the vacuum is metastable, with a lifetime significantly longer than the age of the Universe. For the first time in a global fit of supersymmetry, we employ a consistent methodology to evaluate the goodness-of-fit of the cMSSM in a frequentist approach by deriving p-values from large sets of toy experiments. We analyse analytically and quantitatively the impact of the choice of the observable set on the p-value, and in particular its dilution when confronting the model with a large number of barely constraining measurements. Finally, for the preferred sets of observables, we obtain p-values for the cMSSM below 10%, i.e. we exclude the cMSSM as a model at the 90% confidence level.Comment: 22 pages, 16 figures, to be submitted to EPJ