29 research outputs found
Fittino, a program for determining MSSM parameters from collider observables using an iterative method
Provided that Supersymmetry (SUSY) is realized, the Large Hadron Collider
(LHC) and the future International Linear Collider (ILC) may provide a wealth
of precise data from SUSY processes. An important task will be to extract the
Lagrangian parameters. On this basis the goal is to uncover the underlying
symmetry breaking mechanism from the measured observables. In order to
determine the SUSY parameters, the program Fittino has been developed. It uses
an iterative fitting technique and a Simulated Annealing algorithm to determine
the SUSY parameters directly from the observables without any a priori
knowledge of the parameters, using all available loop-corrections to masses and
couplings. Simulated Annealing is implemented as a stable and efficient method
for finding the optimal parameter values. The theoretical predictions can be
provided from any program with SUSY Les Houches Accord interface. As fit
result, a set of parameters including the full error matrix and two-dimensional
uncertainty contours are obtained. Pull distributions can automatically be
created and allow an independent cross-check of the fit results and possible
systematic shifts in the parameter determination. A determination of the
importance of the individual observables for the measurement of each parameter
can be performed after the fit. A flexible user interface is implemented,
allowing a wide range of different types of observables and a wide range of
parameters to be used.Comment: 32 pages, 6 figures, accepted by Comp. Phys. Com
SUSY Parameter Measurements with Fittino
This article presents the results of a realistic global fit of the Lagrangian
parameters of the Minimal Supersymmetric Standard Model with no assumptions on
the SUSY breaking mechanism using the fit program Fittino. The fit is performed
using the precision of future mass measurements of superpartners at the LHC and
mass and polarized topological cross-section measurements at the ILC. Higher
order radiative corrections are accounted for wherever possible to date.
Results are obtained for a modified SPS1a MSSM benchmark scenario (general MSSM
without assumptions on the breaking mechanism) and for a specific mSUGRA
scenario. Exploiting a simulated annealing algorithm, a stable result is
obtained without any {\it 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.Comment: 3 pages, presented at the 2005 International Linear Collider Physics
And Detector Workshop, Snowmass, CO, 14.-27. August 200
SUSY Tools for Dark Matter and at the Colliders
With present and upcoming SUSY searches both directly, indirectly and at
accelerators, the need for accurate calculations is large. We will here go
through some of the tools available both from a dark matter point of view and
at accelerators. For natural reasons, we will focus on public tools, even
though there are some rather sophisticated private tools as well.Comment: 20 pages, 4 figures, Chapter 16 of the book "Particle Dark Matter:
Observations, Models and Searches" edited by G. Bertone, Cambridge University
Press, http://cambridge.org/us/catalogue/catalogue.asp?isbn=978052176368
Search for Supersymmetry in Final States with Leptons with the ATLAS Detector at the Large Hadron Collider
After a short review of the Standard Model of Elementary Particle Physics and its minimal supersymmetric extension, the MSSM, a global analysis of two highly simplified supersymmetric models, the CMSSM and the NUHM1 is presented, with a focus on the fine-tuning of these models. A new, phenomenologically motivated measure for fine-tuning is introduced. In addition, a search for supersymmetry in final states with four leptons is presented, where a procedure for the consideration of trigger efficiencies with a focus on the calculation of uncertainties on the sum of event weights is given. Finally, limits are set in two simplified models for the direct, associate production of two neutralinos
Physics Beyond the Standard Model: Supersymmetry
This collection of studies on new physics at the LHC constitutes the report
of the supersymmetry working group at the Workshop `Physics at TeV Colliders',
Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the
LHC era, from alternative models and signatures to the extraction of relevant
observables, the study of the MSSM parameter space and finally to the interplay
of LHC observations with additional data expected on a similar time scale. The
special feature of this collection is that while not each of the studies is
explicitely performed together by theoretical and experimental LHC physicists,
all of them were inspired by and discussed in this particular environment.Comment: SUSY workking group report: Les Houches 200