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Trilepton+top signal from chargino-neutralino decays of MSSM charged Higgs bosons

This study presented results from event production using HERWIG and ATLFAST software, focusing on signal and background events for MSSM charged Higgs bosons decays. Various cuts were applied, including lepton, mass, tracking, top, b-tag, and jet cuts. Results were based on a luminosity of 100 fb-1 and highlighted a signal branching ratio of 0.51 for the chosen parameters. Future work includes producing more tt events, exploring additional backgrounds, and conducting 5σ discovery potential scans for various Parameter Sets.

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Trilepton+top signal from chargino-neutralino decays of MSSM charged Higgs bosons

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  1. Trilepton+top signal from chargino-neutralino decays of MSSM charged Higgs bosons 17 June 2004, 9th Nordic LHC Physics Workshop, Copenhagen

  2. Introduction

  3. Introduction (cont)

  4. Introduction (cont)

  5. Event Production • Used HERWIG for event production and ATLFAST for fast detector simulation • Will show results for one point, tanβ = 10 and mA = 350 GeV, in the Parameter Set A • Events produced: • 106 signal events; gb → H+t, H+ → χχ and t → bqq • 107 background events; gg → tt(other bkg channels will be investigated in the future) • Luminosity: 100 fb-1 was assumed • Cross Section: • Signal; NLO σ = 75fb • Bkg tt; Herwig’s logfile σ = 456200fb • Signal Branching Ratio: • H+ is forced to decay to χχ and t is forced to decay hadronically BRTOT = BR(H+→ χχ)*BR(t→bqq) = 0.77*2/3 = 0.51

  6. The Signal

  7. Examples of H+→ 3l+N

  8. Cuts: 3 Lepton Cut

  9. Cuts: Tracking Cut • The isolation criteria in previous cut was only based on ATLFASTs calorimeter • Tracking in ATLFAST gives impractically large files • The “true MC particles” was used to see if any particle was too close (ΔR < 0.3) to any of the three leptons • A track efficiency of 0.9 was assumed* *This is probably an underestimation since according to S. Gadomski (ATL-CONF-2000-009) the efficiency of finding muons is 98% for the Inner Detector

  10. Cuts: Tracking Cut

  11. Cuts: 2l Mass Cut • χ0j→ 2 same flavor, opposite sign leptons + one (or more if j>2) undetectable particle(s) • Out of the three isolated leptons at least 2 are required to have same flavor and opposite sign • The inv. mass of these two is kinematically constrained. For j=2: • If third lepton has same flavor, the biggest Mll are used for the cut 10 < Mll < 63

  12. Cuts: 2l Mass Cut j = 3 Signal events, gb → H+t j = 2

  13. Cuts: 2l Mass Cut background, gg → tt

  14. Cuts: 2l Mass Cut

  15. Cuts: Top Cut

  16. Cuts: B Tag Cut

  17. Cuts: Jet Cut • This cut will be needed only for susy background with many hard jets • For now the parameters are chosen not to decrease the significance of this analysis with only tt bkg

  18. Cuts: Jet Cut

  19. Cuts: Other Cuts

  20. Cuts: Other Cuts

  21. CMS’ Results for this Point

  22. Not Enough MC • 107 tt background events don't give enough statistics • Usedwhere • The Significant with weights = , w = br*cs*L / (# simulated events)

  23. Not Enough MC

  24. Scan Other Sets Background Statistics Pure 3l+N Future Work • SweGrid is right NOW producing more tt events • Look at more backgrounds; ttZ, ttγ, tth, χχ, q, g • Herwig; force χχ→3l+N • BR(H+→χχ→3l+N) from diagrams achieved indirectly from ISAJET • Get significance for points in the tanβ vs. mA plane • Explore the 5σ discovery potential • Make 5σ scans for different Parameter Sets

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