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Manuscript Title: Fittino, a program for determining MSSM parameters from collider observables using an iterative method
Authors: Philip Bechtle, Klaus Desch, Peter Wienemann
Program title: Fittino
Catalogue identifier: ADWN_v1_0 Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 174(2006)47
Programming language: C++.
Computer: any computer.
Operating system: Linux and other Unix flavors.
RAM: ca. 22 MB
Keywords: SUSY parameter determination, simulated annealing, fitting.
PACS: 12.60Jv, 02.70Rr.
Classification: 11.1.
External routines: the ROOT data analysis framework, the SPheno spectrum calculator (included in the distribution). (SPheno may be replaced by any SUSY code which makes predictions for observables and communicates via the SLHA.)
Nature of problem: Provided supersymmetry is realized in Nature, a wealth of data will become available at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). One of the most important tasks will be to extract the SUSY Lagrangian parameters from the measured observables. The large number of SUSY parameters and complicated correlations induced by loop corrections make the parameter determination difficult. Starting a global SUSY parameter fit initialized with tree-level estimates turned out to be an insufficient approach because the MINUIT fitting alogorithm is likely to get stuck in local minima.
Solution method: To overcome the encountered problems without using a priori knowledge, two strategies have been implemented in Fittino. The first one performs the fit in several steps (sub-sector fit method). It starts fitting certain sub-sets of parameters to certain sub-sets of observables and thereby slowly improves the parameter values. Finally the values are good enough to start a global SUSY parameter fit. The second approach uses simulated annealing to improve the tree-level estimates of the parameters to an extent where MINUIT succeeds to perform a global SUSY parameter fit.
Restrictions: The current version of Fittino (version 1.1.1) assumes that there is no CP violation in the SUSY sector, no mixing between generations and no mixing within the first two generations.
Running time: Depending on the complexity of the problem, the running time varies from a few minutes to several weeks.