NIKHEF group meeting

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Current status of my analysisWeekly group
meetingNovember 15, 2001
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T ttbar -gt 6J ins and outs

• Problems
• Too much background
• S/B (qcd mainly) 1/3000 at least
• (run I D0 ttbar-gt6j cross section paper)
• Need some way to distinguish b jets
• (CDF run I got S/B of 1/10 by using impact
  parameter b-tagging)
• Purity most important (dont care much about
  efficiency)

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D0 Run I triggers and cuts
Online Offline
L1 4 trigger towers (ETgt5(7) GeV) 3 tiles (ETgt15 GeV) L2 5 jets 0.3 cone h lt 2.5 HT gt 110(115,120) GeV At least 5 jets 0.5 cone h lt 2.5 ET gt 8 GeV Ignore certain areas Soft muon tag Neural network Loads of MC and DATA for background
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My cuts up to now

• Online Trigger on ANYTHING
• Offline Require 6 jets
• (these are JCCA 0.5 runII cone jets)

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What I did up to now (1)

• Ran over p10.05.00 data
• with Onnes filter framework (thanks!)
• I think these were p10.4 recoed data (not sure)
• Got NO ( events whatsoever
• Went off to Belgium for the Erasmus school

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What I did up to now (2)

• Ran over P10.07 data
• these were reconstructed with p10.07 too!
• Got 10000 events (out of 3 million)
• What was my lumi? Dont know. I started out with
• Some of them actually had an impact parameter
  tag!
• Could not get run and event number from
  root-tuple (problems with Chaining, probably too
  many files)
• Hot towers, no flat f
• No fancy plots, sorry ?

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P10.07 Real data, all 6 jet events This is part
of the sample (700 jets)
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P10.07 Real data, all 6 jet events VERY high jet
multiplicity (NADA is NOT on)
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And then there was light sorry I meant p10.09.00

• No more root macros!
• Luminosity monitoring available
• Unfortunately, there was also
• Shutdown SMT re-cabling
• had to maintain the database, put in dead
  ladders, modified HV scheme.
• more D0trigsim work
• the certification of L3 filters is starting with
  p10.09.00
• Its painful. Several crashes and bug fixes per
  day.
• No time for looking at data

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Plans

• Run over all recent and decent data
• I have the filters ready to do the following
• Get all events with p10.07.00 5 JCCA jets out of
  SAM
• Select them more on the following cuts
• 6 jets, all in h lt 2.5
• HT of total event more than 150
• (This will possibly become my particular trigger)
• Check different permutations of jets and demand
  at least one Z.
• Hopefully this will reduce my background to the
  level where I can look at single events and maybe
  see a real hadronic ttbar event

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Future

• Actual look at new data
• after Thanksgiving
• (Hopefully)