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Lab-wide Run 2 Advanced Analysis Group

Explore multivariate statistical analysis tools for Run II experiments at Fermilab, focusing on evaluating methods, developing tools, and documenting findings to enhance physics analyses.

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Lab-wide Run 2 Advanced Analysis Group

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  1. Lab-wide Run 2 Advanced Analysis Group Pushpa Bhat Fermilab “Keep it simple. As simple as possible. Not any simpler.” -Einstein DØ Collaboration Meeting Apr. 25, 2001

  2. Why Lab-wide (CDF/DØ)? • We may find it necessary to co-operate with the other experiment on important physics analyses • Likely scenario for Higgs discovery: • 5 signal at 115 GeV/c2 requires 15 fb-1 at each experiment and combining the results! Run II Higgs study hep-ph/0010338 (Oct-2000) P.C.Bhat, R.Gilmartin, H.Prosper, Phys.Rev.D.62 (2000) 074022 T.Han, A.S.Turcot , and R.-J.Zhang, Phys.Rev.D59(1999) April 25, 2001 D0 Collaboration Meeting P. Bhat

  3. Run2AAG - Brief History • Desirability of such a group expressed at ACAT2K and Top Thinkshop-2 by CDF, DØ physicists • Had discussions with CDF/DØ spokespersons, Directorate • Presentations at a couple of CDF meetings • One-day mini-workshop on Feb. 10, 2001 • ~70 people from CDF/DØ • Opening by Mike Shaevitz • Many talks + tool-kit demo • Identified sub-groups • A few meetings since the workshop • See http://www-d0.fnal.gov/~pushpa/run2aag/ April 25, 2001 D0 Collaboration Meeting P. Bhat

  4. Run2AAG • Focus: Multivariate & Statistical Analysis Issues for Run II • Goals: • Learn and discuss • Explore, develop & adopt tools • Evaluate Methods • Document tools, studies, findings  Generate a report • Agenda: • Driven by the participants April 25, 2001 D0 Collaboration Meeting P. Bhat

  5. Run II Advanced Analysis Working Groups • Tools • Provide convenient interfaces to useful algorithms and software, in an experiment-independent manner • Simulation • provide simulated data in a convenient form for evaluation studies • Evaluation • Evaluate methods with a few example studies • Statistics • Address statistical analysis issues April 25, 2001 D0 Collaboration Meeting P. Bhat

  6. Tools Group • Develop methods/tools, discuss ideas, share understanding. • Develop tools/interfaces in such a way that it is not tied to a particular experiment • Usable in ROOT, Python or in C++ • Example Algorithms: Neural Networks (Jetnet, MLPfit, …) RaGS (Random Grid Search) PDE (Probability Density Estimation) PCA (Principal Component Analysis) ICA (Independent Component Analysis) Bayesian Fit Markov Chain Monte Carlo (for multivariate Bayesian analysis) April 25, 2001 D0 Collaboration Meeting P. Bhat

  7. Tools • Prior to Run2AAG • Tools developed for Run 1 analyses RaGS, H-matrix, NN(Jetnet) Interface, BayesFit (Bhat, Prosper, Stewart,…) PDE (Rice Univ. Group) RGSHelper, Sleuth (Knuteson) • A Python tool-kit (based on C++ wrappers) for a number of multivariate and event generator/simulator packages (H. Prosper) • dØMA – a DØ multivariate package of useful tools • Now • Python tool-kit development continues • Will be available from Run2AAG web page • dØMA now evolved into TerraFerMA (S.Towers, D.Chakraborty, S.Desai, J.Hobbs) • See http://www-d0.fnal.gov/~smjt/ April 25, 2001 D0 Collaboration Meeting P. Bhat

  8. Multivariate Analysis Issues • Dimensionality Reduction • Choosing variables optimally without losing information • Choosing the right method for the problem • Controlling Model Complexity • Testing Convergence • Validation • Given a limited sample what is the best way? • Computational Efficiency April 25, 2001 D0 Collaboration Meeting P. Bhat

  9. …Multivariate Analysis Issues • Correctness of modeling • How do we show that the background is modeled well? Is it sufficient to check the modeling in the mapped variable? Pair-wise correlations? Higher order correlations? • How do we quantify the correctness of modeling? • In conventional analysis, we normally look for variables that are well modeled in order to apply cuts • How well is the background modeled in the signal region? • Robustness of the results • How do we check the robustness? • For each specific case, should we distort our modeling and study the effect on the results? April 25, 2001 D0 Collaboration Meeting P. Bhat

  10. Simulation • We anticipate providing ntuples that contain Monte Carlo simulations of Higgs, SUSY, Single Top events, etc., together with the most important backgrounds. • Use PGS (Pretty Good Simulator, formerly SHW), developed for SUSY/Higgs Workshop. Provides a fast simulation (thought to be accurate to about 15%) of  the response of typical collider experiments to high energy collision events. April 25, 2001 D0 Collaboration Meeting P. Bhat

  11. Evaluation • Use example physics analyses for evaluating methods/tools • Improve several aspects of analysis • Develop methods for sophisticated multivariate cross-checks April 25, 2001 D0 Collaboration Meeting P. Bhat

  12. Statistics • Statistical procedures • Review what we do & the literature • Discuss and study • Develop recommendations • Make information available on the Run2AAG web site • Web pages of BaBAR and CDF statistical committees will be accessible • Louis is in touch with the BaBAR Group • Documentation from CERN workshops • We also receive minutes from CDF statistics committee. CDF statistics committee will meet with DØ counterparts once in three months or so April 25, 2001 D0 Collaboration Meeting P. Bhat

  13. … Statistics • Sample issues: • Systematic uncertainties • What are they? • Can they always be disentangled? • Those connected with theory options • Modeling of errors • Gaussian error on efficiency? • Confidence Levels, Limits • Bayesian approach • Priors • Model comparisons • Combining results April 25, 2001 D0 Collaboration Meeting P. Bhat

  14. Please come and participate! Next meeting: May 24, 2001 http://www-d0.fnal.gov/~pushpa/run2aag/ (Temporary location) Run2AAG web pages need a Web Master from DØ. Tony Vaiculis (CDF) April 25, 2001 D0 Collaboration Meeting P. Bhat

  15. Home Page Mini-Workshop Next Meeting Working Groups Proceedings Documentation Interesting Sites RUNII ADVANCED ANALYSIS METHODS GROUP • Chief Co-ordinator: Pushpa Bhat • ConvenersPushpa Bhat (D0/Fermilab)Phil Koehn (CDF/OSU)Louis Lyons (CDF/Oxford)Harrison B. Prosper (D0/FSU) • Goals • Explore and develop advanced analysis methods & tools • Perform example analyses • Serve as a resource to the experiments at the Tevatron • Agenda • Study and evaluate Multivariate analysis methods, e.g.: • Random Grid Search, Neural Networks, Probability Density Estimation Methods, Genetic Algorithms, PCA, ICA, IDA, .. • Build analysis tools for use in friendly environments, e.g.: • Python, JPython • Matlab, Mathcad • Address Statistical Analysis Issues • Signal Significance, Confidence Limits, Comparing Hypotheses, Combining Experiments, etc. http://www-d0.fnal.gov/~pushpa/run2aag/ April 25, 2001 D0 Collaboration Meeting P. Bhat

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