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Arguments for a “low mass” Higgs

Low Mass Higgs @ LHC Why low mass? Production characteristics Decay characteristics Overview of search strategies or who does what and how does it hang together. Arguments for a “low mass” Higgs. 114 < m h < 200 @95%CL in SM LEP saw enhancement at 115 GeV. SUSY favors m h <135GeV.

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Arguments for a “low mass” Higgs

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  1. Low Mass Higgs @ LHCWhy low mass?Production characteristicsDecay characteristicsOverview of search strategiesorwho does what and how does it hang together

  2. Arguments for a “low mass” Higgs • 114 < mh < 200 @95%CL in SM • LEP saw enhancement at 115 GeV. • SUSY favors mh<135GeV

  3. NLO Cross sections M. Spira et al. gg fusion IVB fusion SM Higgs at LHC: ~10-40pb

  4. Other SM Physics Xsections(crude guestimates) • Total Xsection = 1011pb • b-quark pT>30GeV = 106pb • W-> e/mu nu = 5x104pb • Top-quark = 860pb => Always gives WW • WW from QCD = 100pb • Higgs = 10pb

  5. pb ->

  6. When WW channel opens up pronounced dip in the ZZ BR … SM Higgs Decays WW favored over ZZ by a factor 4-50 !!!

  7. CMS L1 Trigger • Di-electron/photon • Di-muon => Only di-photon, WW, and ZZ decays matter

  8. W,Z, and tau decays • W: • 10% to lepton & neutrino for each e,mu,tau • 70% to di-jet • Z: • 3.4% each ee, mu mu, tau tau • 20% for di-neutrino • 70% for di-jet • Tau: • 35% for e or mu plus 2 neutrinos • 50% for other “1-prong”

  9. Some di-boson BR’sll = ee or mumutt = tau tau = two isolated tracksjj = di-jet • BR(WW -> lnu lnu) = 4x1% = 4% • BR(ZZ -> llll) = 4x0.1 % = 0.4% • BR(ZZ -> lltt) = 4x0.08% = 0.3% • BR(ZZ -> llnunu) = 2x0.7% = 1.4% • BR(ZZ -> lljj) = 2x2.4% = 4.8%

  10. Higgs Search Strategies • 2 leptons & missing ET • Shih-Chieh’s thesis at CDF • Covers 3% of total BR(H->llnunu) • Di-lepton & di-jet • Matthew @ CDF for mH = 150GeV sweatspot • Covers 2.4% x 8% = 0.2% • Traditional 4 leptons • Covers 0.4% x 8% = 0.03% @ 150GeV sweatspot • ll track track may double this if we’re lucky ? • Kevin @ CDF in WZ mostly

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