DC 04, etau request

1
DC 04, e-tau request

• G. Leibenguth, O. van der Aa
• Institut de Physique Nucléaire
• Louvain-la-Neuve

2
Philosophy

• Reminder Data Challenge (DC 04) is the test
  of
• Analysis of 50 million events after the HLT,
  corresponding to 25 Hz at a luminosity of.
• 0.2 1034 cm-2 s-1 for a period of one month.
  This represents 6.
• fb-1.
• Assumption
• 2 million of events can be digitized for the
  e-tau channel.
• The expected number of event (HLT offline) is
  taken from the CMS note 1997/106 (Sasha Ritva)
  which was estimated for a lumi of 30 fb-1.
• Minimize the number of cuts (at generation
  level) to make rate and efficiency studies at HLT.

3
Reminder e-? Threshold
Trigger Rate (Hz)
Trigger absolute efficiency
etau additionnal rate
etau additionnal efficiency
single e rate
single e efficiency
Single electron threshold 28 GeV _at_ L1 ? 6.5
kHz e-? threshold 2062 GeV _at_ L1 ? additional
1 kHz The addition of the e-tau trigger increase
the efficiency by 10 . The rate increase by the
etau trigger at L2.5 is 7 Hz.
4
Background Type, ? and Br

• Br is given according to the final state
• ?jet all hadronic decay of the tau lepton
• Lepton ( l ) stands for electron or muon.
• tt cross section at leading order (LO)

Invariant mass gt 130 GeV 2 jets Ptj gt 15
GeV/c, ? lt 3.2
Most of the number are taken from the ATLAS
physic TDR
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Procedure
Expected number of events for Lint 6 fb-1
Lepton ( l ) stands for electron or muon.
6
Signal H/A ? e-?
4 hypothesis 1) MA 200 tan ? 10 2)
MA 500 tan ? 10 3) MA 200 tan ? 20 4)
MA 500 tan ? 20
25 000 each.
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Request

• What can be produced directly from the last
  table
• 100 K Drell-Yan cut on the invariant mass of
  the lepton at generator level Minv gt 110 GeV (we
  can afford a smaller cut than 130) .
• 300 K ttbar with l ?jet, no cut in Pt.
• What needs to be investigated in detail for
  tWb, Wjet and bbbar
• number of event rejected by applaying a low Pt
  threshold on lepton and tau jet Pte gt 4 GeV or
  Pt?jet gt 20 GeV.
• Rate bias at HLT induced by such thresholds.
• What remains to be further investigated
• number of events selected after HLT to know how
  many events are going to be written on tape. The
  new HLT trigger code will be used to obtain these
  numbers.