71 research outputs found
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
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