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SM Higgs in the 160-250 GeV Mass range

SM Higgs in the 160-250 GeV Mass range. Paul Derwent FNAL/Beams Division/Pbar/CDF 4 May 2001. Standard Model Higgs above WW Threshold. Dominated by WW Depends on weak coupling constant g and kinematic constraints for on-shell W bosons Above 2M Z significant contributions from ZZ

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SM Higgs in the 160-250 GeV Mass range

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  1. SM Higgs in the 160-250 GeV Mass range Paul Derwent FNAL/Beams Division/Pbar/CDF 4 May 2001

  2. Standard Model Higgs above WW Threshold • Dominated by WW • Depends on weak coupling constant g and kinematic constraints for on-shell W bosons • Above 2MZ significant contributions from ZZ • Test: Higgs coupling to weak gauge bosons • Mass coupling? • For bbar b? small coupling! • Others even smaller!

  3. Higgs Branching Fractionsfrom HDECAY

  4. Simple Statistical Analysis • For measuring branching fractions: • Numerator: identified Higgs decays to WW • Denominator: number of Higgs produced • Use process e+e--> ZH • Followed by Z->e+e- or Z->µ+µ- • Identify Higgs via Missing Mass Technique • Mass recoiling against Z • Assume 80% efficiency in finding events of this type • Measure Numerator and Denominator in same dataset • Independent of luminosity and cross section calculations

  5. Scenarios • Cross Section for Associated Production from W. Kilian, M. Krämer, and P.M. Zerwas, hep-ph/9605347 • SM Branching ratios from HDECAY A. Djouadi, J.Kalinowski, and M. Spira, Comput. Phys. Commun. 108, 56 (1998) • Scenario 1: • Gauge Boson Decays • √s = 500 GeV • 250 fb-1 • Scenario 2: • Rare Decays • √s = MZ+MH+50 GeV (optimal value) • 2000 fb-1 10 fb-1 = 107 seconds at 1033

  6. Scenario 1 • WW ID: • ≥ 50% • ≥150 events ≤10% Statistical uncertainty

  7. Scenario 1 • ZZ ID: • Leptons only • ~40% • ≤ 60 events ≥13% Statistical uncertainty Difficult below 2MZ • Distinguishing ZZ hadronic decays from WW challenging but could add significantly to this channel • b bbar very difficult for MH > 160

  8. Scenario 2 • WW even easier • ZZ straightforward for MH > 2 MZ • b bbar still somewhat problematic

  9. Scenario 2 • b bbar • 90% ID for 1 b • Problematic for MH >2MZ

  10. Scenario 2

  11. Things to consider • Include WW fusion production process • Increase number of Higgs • How to identify as Higgs events? • Include background processes • ZZ* and Zg expect to be important • Can we distinguish H->ZZ from H->WW hadronic decays? • Simulation/detector design question

  12. Conclusions • For MH > 2 MW • SM Higgs decays dominant to gauge bosons • Measurement of BR(H->WW) straightforward • Could distinguish SM Higgs from non-SM Higgs • Difficult to measure coupling to fermions • Requires significant luminosity for b bbar • t t and c cbar probably not possible

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