SM Higgs Boson Discovery Potential at CMS via Weak Boson Fusion

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SM Higgs Boson Discovery Potential at CMSvia
Weak Boson Fusion

• A. Mestvirishvili, U. Akgun, A .S. Ayan, F. Duru
• E. Norbeck, Y. Onel, S. Wang
• The University of Iowa

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Higgs Production

• Theoretical studies do not give a prediction for
  the Higgs mass.
• LEP II has set a lower limit at 114.4 GeV/c2.
• The WBF (Weak Boson Fusion) production scheme
  has the second largest
• cross-section after gluon-gluon fusion.

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Higgs Decay

• This study is concerned with the Higgs particle
  production by WBF with
• subsequent H decay to a pair of Zs.
• Three different values for the Higgs particle
  mass were selected for this study
• 300 GeV/c2, 350 GeV/c2, and 500 GeV/c2

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Event Generation and Reconstruction

• We used PYTHIA 6.2, CMSIM , ORCA 7.6.0, with
  pileup
• No tracker was simulated, e e- were selected
  from generator particle information
• ZZ, W?ZZ, and Zjets are neglected due to either
  low cross-section or negligible after the cuts.

Higgs and Z decay mode H ? Z0Z0 ? ee-?e?e
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Pre Selection Cuts

• Leptons (e e- ) were selected from generator
  particles data, with
• -2.4 lt ? lt 2.4
• Lepton cuts ET gt 20GeV and
• M(e e-) - M(Z) lt 15GeV
• Leptons are between tagged jets
• Missing ET gt 10 GeV
• Either 2 forward jets or 2 central jet or 1
  forward and central jet

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Missing Transverse Energy
a) 300 GeV, b) 350 GeV, c) 500 GeV, d) t t Cut
for reconstructed Missing ET gt 50GeV
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The Jets

• Eliminate the possibly fake jets due to electrons
  (?R gt 0.5)
• Jets must be in opposite hemisphere ?1 . ?2 lt 0
• ? difference between jets greater than 4.0
• If more than one pair of jets found, the pair
  with largest ? difference are tagged
• If no such pair is found, event is dropped

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Tagged Jets
E t of tagged jets Green Higgs 300 GeV Red
Higgs 350 GeV Blue Higgs 500 GeV Black - ttbar

• Iterative Cone Algorithm, cone radius 0.5, with
  Et gt 20 GeV
• Jets are within CMS detector acceptance ? ? 5
• Majority of the events have at least one pair of
  tagged jets

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Dijet Mass Cut
DiJet mass distribution for the signal and
background events.
Cut is applied at 500 GeV
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Central Jet Veto
Central jet veto is very efficient tool to reduce
the background since signal events in qqH
processes tend to have either no or small
central jet activity. Jets in the background
events tend to be central.
Fraction of events containing at least one jet in
the ? region covered by the tracker.
Fraction of the events with two forward tagging
jets and at least one jet in the central region
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Central Jet Veto Acceptances Significance
Overall acceptances for the signal and background
events after applying all the selection cuts.
When central jets were vetoed before (first row)
and after (second row) forward jet tagging were
performed.
By changing the order of the cut application, a
reduction factor 3 is achieved for the
background events, while the acceptance for the
signal events is reduced by factor 1.4 - 1.5.
By this way we do not need B-Tagging.
.
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Extrapolated Significance
This study covers only one decay combination of
six different possibilities for the signal
But, for background decays there are only two
possible decays
Extrapolated significance For 60 fb-1 data
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Summary