The Origin Of Electro-Weak Symmetry Breaking

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SUSY Higgs Pair Production at LC 500/800/1000
Klaus Desch, Tatsiana Klimkovich, Thorsten Kuhl,
Alexei Raspereza University of Hamburg/DESY ALCPG
meeting - SLAC 09/01/04
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Motivation

• Detection of heavy neutral Higgs Bosonsdifficult
  at LHC in parts of parameter space
• Important to disentangle structure of
• Higgs sector (2HDM, more singlets etc?)
• Heavy Higgs sector helps a lot in the
  determination of SUSY parameters
• (e.g. sensitivity to tanß, see Gunion et al)
• No detailed experimental study so far.
• Questions
• Which decay modes can be measured ?
• Precision on rate (for which vs, L,) ?
• Precision on massses ? Mass splitting ?
• Distinguish H and A ?
• Can the decay width be measured ?
• CP violation ? (mixtures)

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Simulation

• PYTHIA for signal background generation
• CIRCE for beamstrahlung
• SIMDET for fast (TESLA) detector simulation
• b tagging with ZVTOP based ANN
• basic tau ID
• kinematic fits (DELPHI package)
• Study a grid of A/H masses for
• 500 fb-1 at vs500 GeV, 800 GeV (and 1 point at 1
  TeV)
• Signal cross section s(HA) sin2(ß-a) ? sSM(HZ)
  
• We assume sin2(ß-a) 1 and
• BR(H/A?bb) 0.9, BR(H/A?tt)
  0.1

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Signal grid
note in decoupling limit CP conserving MSSM,
normally mAmH but large ?m may appear e.g. if CP
violation is present
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Backgrounds
rather complete SM BG sample o(30 M) events in
total
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Selection Strategy
HA? bbbb

• cut based selection using
• event shape
• jet btags
• kinematic fit (4C)
• 3 di-jet combinations (take them all)
• reconstruct SM and ?M
• Efficiency 40 Accepted background 4/1 fb
  (500/800 GeV)

HA? bbtt

• likelihood selection using
• 4 jet events (2b and 2t)
• t jets low multiplicity (1 or 3 tracks)
• LH event shape b tags
• kinematic fit (assuming tau-jet direction tau
  direction)
• reconstruct tt mass and bb mass
• Efficiency 30-45 Accepted background 2-6 fb

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Results bbbb
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Results bbtt
allows for relative BR determination of the two
Higgses individually!
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Results bbtt mass degenerate case
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Results
Precision on rate
Precision on mass
precise 5s discovery reach to be determined
vs/2 50 GeV for bbtt higher for bbbb
(for mass-deg. case)
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SPS1a Results
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Decay Width Measurement?
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Decay Width Measurement?
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Summary Conclusions

• Experimental study of heavy SUSY Higgs bosons
  LC note ready this month
• Rates for bbbb and bbtt can be measured with
  level accuracy
• Masses can be measured to o(1 GeV) precision up
  to few tens of GeV below kinematic limit
• First attempt to measure total width (lineshape)
  resolution few GeV if enough rate from bbtt
• H/A of SPS1a can be measured at 1 TeV machine
• (can be used as input to overall SUSY
  parameter fits)
• Also non mass-degenerate case studied
• (can be used as input to CP violation studies)
• To be done SUSY decays, interpretation in SUSY
  models