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Progress on SUSY particles reconstruction methods

This study by Massimiliano Chiorboli from the Università di Catania explores methods for reconstructing SUSY particle masses using low integrated luminosity, focusing on mSUGRA benchmark points proposed after LEP. It details how high total SUSY cross-sections enable mass reconstruction through analysis of decay chains and event topologies, involving isolated leptons and b-jets. The work discusses event selection criteria and reconstruction techniques, including combinatorial suppression and estimation methods, highlighting the potential for accurate mass estimation amidst significant background challenges.

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Progress on SUSY particles reconstruction methods

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  1. Progress on SUSY particles reconstruction methods Massimiliano Chiorboli Università di Catania

  2. mSUGRA Points Proposed Post-LEP Benchmarks for Supersymmetry (hep-ph/0106204) High total SUSY cross section we can try to reconstruct masses with low integrated luminosity Massimiliano Chiorboli

  3. Point B Massimiliano Chiorboli

  4. (26 %) (35 %) (0.2 %) (60 %) p b b p Decay chain and event topology • Event final state: •  2 high pt isolated leptons OS •  2 high pt b jets • missing Et Massimiliano Chiorboli

  5. Events Production • SPYTHIA (PYTHIA 6.136) • CMSJET 4.703 No pile-up Massimiliano Chiorboli

  6. Events selection • at least 2 isolated leptons with pt>10 GeV and |h|<2.5 • at least 2 b-jets with pt>15 GeV and |h|<2 Massimiliano Chiorboli

  7. SUSY SM SUSY + SM Reconstruction of PYTHIA Signal CMSJET Massimiliano Chiorboli

  8. Reconstruction of Subtracting invariant mass of OSOF pairs eliminate tt and combinatorial bkg, but not Z+jet Other cuts Massimiliano Chiorboli

  9. Reconstruction of Massimiliano Chiorboli

  10. Reconstruction of Result of fit: Generated value: Massimiliano Chiorboli

  11. reconstruction Massimiliano Chiorboli

  12. Sbottom reconstruction reconstructed neutralino combined with the most energetic b-jet, assuming Mc1known Cutting on Etmiss allows to suppress the SM bkg Massimiliano Chiorboli

  13. Etmiss > 100 GeV Etmiss > 150 GeV Sbottom reconstruction 10 fb-1 2 sbottoms we can’t resolve the 2 peaks Massimiliano Chiorboli

  14. M(b) estimation Result of fit: Generated masses: Massimiliano Chiorboli

  15. Estimation of Mllbmax PYTHIA Signal total Massimiliano Chiorboli

  16. Estimation of Mllbmax Result of fit: Massimiliano Chiorboli

  17. Gluino Reconstruction Another b-jet is associated to the recostructed sbottom the b-jet closest in angle to the reconstructed sbottom is chosen Massimiliano Chiorboli

  18. Gluino Reconstruction Etmiss > 50 GeV Etmiss > 100 GeV Etmiss > 150 GeV Massimiliano Chiorboli

  19. Gluino Reconstruction Result of fit: Generated mass: Massimiliano Chiorboli

  20. Combinatorial suppression Massimiliano Chiorboli

  21. Gluino after angle cut 10 fb-1 Massimiliano Chiorboli

  22. Sbottom after angle cut 10 fb-1 Massimiliano Chiorboli

  23. Estimation of doesn’t depend on M(c10) ! Massimiliano Chiorboli

  24. Estimation of Result of fit: From the model: Massimiliano Chiorboli

  25. Sbottom and Gluino reconstruction With 40 fb-1 No angle cuts Only SUSY Etmiss > 150 GeV sbottom gluino Massimiliano Chiorboli

  26. Generated values With 40 fb-1 sbottom Massimiliano Chiorboli

  27. With 40 fb-1 gluino Generated value Massimiliano Chiorboli

  28. With 40 fb-1 no f cut Massimiliano Chiorboli

  29. m0 120 GeV g 919.8 tL 589.4 m1/2 375 GeV bL 723.0 tR 800.8 tan b 20 bR 771.3 c40 545.3 A0 0 sign m + qL 814 c30 532.4 qR 780 c20 294.8 lL 299.6 c2± 546.1 lR 193.4 c1± 294.5 c10 = LSP 152.5 Point G Massimiliano Chiorboli

  30. (26 %) (44 %) (8.8 %) Point G Massimiliano Chiorboli

  31. Conclusions Point B, with 10 fb-1 • estimation of M(l+l-)max • estimation of M(l+l-b)max • sbottom reconstruction with Resol. ~ 10 %, but 2 sbottoms not resolved • gluino reconstruction with Resol. ~ 12 % • M(g) - M(b) estimation, independent from M(c10), with Err ~ 7 % Point G, with 60 fb-1 • No sbottom reconstruction, needs more investigation Massimiliano Chiorboli

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