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Advanced Analysis Methods for Higgs in Run II

This workshop by Pushpa Bhat discusses advanced analysis methods for studying low-mass Higgs bosons and optimizing signal-background discrimination in collider experiments. Topics covered include b-tagging, mass resolution, and neural network applications.

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Advanced Analysis Methods for Higgs in Run II

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  1. Advanced Analysis Methods for Higgs in Run II Pushpa Bhat Fermilab Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  2. Collaborators: • R. Gilmartin • H. Prosper • Run II SUSY/Higgs Working Group P.B., R.G., H.P., PRD 62, 074022 (2000) Run II Higgs Working Group Report, hep-ph/0010338 For a discussion of Advanced Methods, see my video-streamed plenary talk at: http://conferences.fnal.gov/acat2000/ Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  3. Outline • Low mass Higgs MH < 130 GeV/c2 • WH, ZH Production • Experimental Issues • Signal-background discrimination • b-tagging • Mass resolution • Conclusions Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  4. Low Mass Higgs Study • Signals: • Channels: Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  5. Signal WH Backgrounds Wbb WZ tqb tb ttbar Detector Simulation SHW Networks Jetnet (v3.0) 3 Networks/MH WH vs WZ WH vs Wbb WH vs tt 3 cuts WH  lbb Single Lepton Channel (7,9,1) Network Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  6. WH(100 GeV/c2) vs. WbbVariables Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  7. WH(100 GeV/c2) vs. WZVariables Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  8. WH(100 GeV/c2) NN Distributions Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  9. Optimizing Cuts (WH100) Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  10. WH(110 GeV/c2) NN Distributions Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  11. NN Learning Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  12. Discriminating Surface Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  13. Standard vs. NN Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  14. Combined Network NN1 WH-Wbb NN2 WH-WZ NN4 NN3 WH-top NN4= f (NN1,NN2,NN3) • Use in fitting distributions • Use in mass measurement Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  15. Combined Network (WH110) Currently see no improvement in significance by fitting the NN distributions for single lepton channel. This is work in progress Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  16. bottomcharmprimary Points- single m data, black - fit. b-Tagging • LEP experiments have impressive b-tagging using Neural Networks • Use Neural Networks to combine lifetime and kinematic variables • Work in progress at CDF & DØ • R. Demina 60% better eff*purity than conventional • S. Repond (ACAT2K Proceedings) P b b jets Non-b jets Channel-dependent b-tagging Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  17. Jet Energy Corrections Example: Correct jet energy using transverse energy and eta. Use NN to fit the correction function  Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  18. Mass Another approach: Find the parameters for energy correction by minimizing the variance in Mbb directly Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  19. Higgs Mass Fits S= 80 WH events Wbb used as Background S/B =1/10 Mfit =114 11 GeV/c2 S/B =1/5 Mfit =114  7 GeV/c2 Method:P.B., H.P., S.Snyder, PLB 407, 73 (1997) Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  20. Work in Progress • Systematic selection of variables • Continue study of b-tagging, mass resolution. • Fit distributions instead of counting above cuts, and use new results in all channels • Continue to develop Bayesian method for combining channels. • Study effect of various systematic uncertainties on discovery reach. Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  21. Conclusions • Finding Higgs at the Tevatron will be extremely challenging! • As evidenced from work at LEP, we will need all the sophistication in analysis that we can acquire. Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  22. Back-up Slides Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  23. Mbb HT Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

  24. Higgs Mass Resolution Use mjj and HT (= Etjets ) to train NNs to predict the Higgs boson mass 13.8% 12.2% 13.1% 11..3% 13% 11% Future of Higgs Physics Workshop May 3-5, 2001 Pushpa Bhat

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