Electron Triggering and B-Physics at L3 (B?J/?Ks, where J/? ?e?e?) Abid Patwa, Andr

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Electron Triggering and B-Physics at L3(B?J/?Ks,
where J/? ?e?e?)Abid Patwa, André Turcot, and
Sailesh ChopraB-id Vertical ReviewDØ,
FermilabWednesday, April 4, 2001
AGENDA

• Motivations for Study and Trigger Constraints
• Summary of Previous Studies and Work
• L1 and L2 study of J/? ISAJET events
• Current Work Studies
• L3 filtering using TRK, CPS and CAL information
• Progress report
• Overview
• Resolution Study Matching, Invariant Mass
• Preliminary efficiency results
• Future Plans and Proposals

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Motivation for Study

• Maintain B-physics analysis with high statistical
  sample
• Use electron decays of J/?s in addition to muons
• Calibration of detectors in low energy range
• reconstructed J/? mass
• understand detector alignments ? fit M J/? to
  alignment constants
• Establishing relative energy scales between the
  CC and EC
• coupled to preshower readout capabilities
• AFE12 board -- dual threshold, charge division,
  etc

Necessary to understand trigger resolution and
efficiencies for all of the above issues
Constraints for J/? ?e?e? trigger

• L1 accept rates defines J/? trigger rate 1.5kHz
  for both central/forward region
• L2 accept rate below a maximum of 100 Hz
• L3 accept rate kept below 1-5 Hz

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Summary of Trigger Studieswith electrons from
J/?s

• Initial L1 and L2 studies performed
  (mainly upgrade GEANT)
• DØ Note 3249 by Y. Gershtein
• low pT electrons from b-quarks
• central region -1.5 ? ? ? 1.5
• algorithm combined CFT tracks and CPS hits
• DØ Note 3506 by P. Grannis
• J/? trigger in central region (ISAJET)
• algorithm combined CPS and CC info
• Results efficiencies 6-10 achieved, dependent
  on CC thresholds
• Reasonable trigger rates L1 ? 1 kHz and L2 ? 50
  Hz
• DØ Note 3566 by A. Lucotte
• J/? trigger in forward region (ISAJET)
• algorithm combined FPS and EC info
• reconstructed events processed with upgrade GEANT
• Efficiencies as function of FPS strip and ECEM
  thresholds, Inv. Mass dist.,... see DØ Notes for
  details
• Further studies at L1, L2 ?

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L3 Electron Studies (J/?? e?e?)A. Patwa, A.
Turcot, et. al.

• Initial work in past 4-5 months
• Unsuccessful for physics studies
• Modified electron results CAL and CPS info
• Number of code breaks, tsim_l3 output crashes
• incompatible datafiles with L3 code require
  generating files with RawDataChunks
• Short-term
• Given limited statistics in MC, develop machinery
  for future studies with larger samples ?
  standard Root macro
• Establish foundation
• Long-term
• Extract efficiencies, purity, invariant mass
  dist.,
• Understand backgrounds, etc...

Proposal
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L3 Electron Studies J/??ee (cont.)

• Sample
• processed under dØsim p07.00.03
• J/?? e?e?, 1000 events total (two 0.5K files)
• Event selected pythiaQQ PT (B) ? 3.0 GeV
• at least 2 electrons with PT (e) ? 1.0 GeV, ?
  ? 2.5
• Avg. min. bias overlay NMB1.1, Poisson
  distribution
• Sample processed under p06.00.01 (mod) dØTrigSim
• Modifications in dØTrigSim
• l3fanalyze
• change track extrapolation to 73.96 cm (CPS) from
  60 cm (Solenoid)
• l3fcps
• change max number of SLCs from 31 to 63
• l3femtools
• change call to L3TCPS to not use z information
• change call to L3TCPS to use log weighted Phi
  position
• Note CAL cluster is taken wrt to PV, but PV used
  is not stored (p06.00.01)
• trig_mcc3.lst
• change PT(e) threshold for CFT tracks from 3 to 1
  GeV

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L3 Electron Studies (cont.)

• Primary L3 Ntuple variables studied
  (Global.L3DebugE)
• currently available in l3fanalyze (I.e., running
  d0trigsim)
• TRK
• L3DEntracks -- Number of tracks
• L3DETrphi -- Track Phi
• L3DETrZ -- Track Z (wrt PV)
• L3DETrPtinv -- Track 1/PT
• L3DETrR -- Track radius of curvature R
• L3DETrTanl -- Track Tan(?), ? tracks dip
  angle
• CAL
• L3DEncal -- Number of CAL clusters found by
  L3TCalCluster
• L3DECalPhi -- Cal cluster Phi (vector sum)
• L3DECalEta -- Cal cluster Eta (vector sum)
• L3DECalWZ, WR, Wphi -- Cal (log-weighted sum) Z,
  R, phi
• L3DECalEt -- Cal cluster measured Et
• L3DECalEmfr -- Cal cluster EM fraction
• L3DECalEfr1, L3DECalEfr5 -- Cal cluster E frac.
  in EM1, ,EM4, FH1

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L3 J/? Studies Matching Resolution
Comparison MC electrons with tracks (TRK) and CAL
CAL-MC TRK-MC
??
??
CAL-MC TRK-MC
??
??

• Use MC information
• identify only e? in data sample, PT ? 1 GeV
• Electrons tagged by matched tracks
• Require ?R ? (??2 ??2) ? 0.07
• Basic Approach
• Study matching performance for tagged e? by
  cycling/pairing subsystems CFT, CPS and CAL

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J/? electrons Matching Resolution TRK-CAL
Tagged e? CFT tracks and CAL clusters
??
??
??
??
?R

• Resolution in ? RMS 63 mrad
• okay central core, dominated by tails
• may need some improvements
• Benchmark compare to other L3 electron studies
  (Z? e?e?, Upsilon ? e?e? ) RMS ? ?(10-25 mrad)
• ?-matching ? long tails
• Track ? assumes zo of track as primary
• under investigation probable effect from CAL ?
  determination (primary vertex info)

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J/? electrons Matching Resolution CPS-CAL
Tagged e? CPS clusters and CAL clusters
??
??
??
??
?R

• Resolution in ? RMS 29 mrad
• better, but may need some more work...
• ?-matching ? long tails
• Similar to TRK-CAL
• CPS ? assumes zo of tagging track as primary

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J/? electrons Matching Resolution CFT-CPS
Tagged e? CFT tracks with CPS clusters
?z
??
?z
??
?? ? -??

• Improved resolution in ? RMS 6.1 mrad
• Two peak distribution from track propogation
  (B-Field)
• separated ?ve and ?ve tracks at ?? 0
• effect known, see A. Turcots study on
  Electron-ID using CPS, L3fcps on b-id
  documents web-page
• ?? ? ??? for ?ve tracks improves RMS 4.5 mrad
• z-matching needs work
• indications are that ?z(trk) is dominant

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J/? electrons Invariant Mass
For tagged e? MC, CAL, CAL-TRK, TRK
MC CAL
M(ee)
M(ee)
CAL-TRK TRK
M(ee)
M(ee)

• Calculation based on

• TRK gives mass closest to expected
• CAL energy scale is off
• requires work...
• TRK-CAL calculation
• driven by CAL energy scale
• Comment substantial improvement in M(ee) with
  CFT PT 3 ? 1 GeV (trigger list modification)

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J/? electrons Matching Efficiency
For tagged e? Initial Result on Matching
Performance

• Very Preliminary but a start
• Substantial improvement with CFT PT 3 ? 1 GeV
  (trigger list modification)

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Selection Criteria

• Develop electron selection criteria
• Try at best to optimize selection, very
  preliminary
• again, No L1 and L2 applied
• Basic selection cuts
• kept loose (now)
• CAL ET ? 1 GeV, ? ? 2.0, Efrac ? 0.8
• Define CAL-TRK match ?? ? 0.07
• Define CAL-CPS match ?? ? 0.05
• Classify electrons in four categories
• 1) Golden Electron TRK, CPS, CAL
• 2) CPS-CAL only
• 3) TRK-CAL only
• 4) CAL only
• For J/?
• consider only Type 1 and 3 electrons
• controlling trigger rates requires at least a
  track

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J/? electrons Selection Criteria e?-types
(cont.)
J/? Signal Event Selection

• B?J/?Ks, where J/? ?e?e? 1K sample
• Most candidates are Golden

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J/? electrons Selection Criteria (cont.)
Invariant Mass electron selection criteria
applied
CAL info TRK
M(ee)
M(ee)
CAL-CPS
M(ee)

• Calculation based on

• Similar to results from MC tagged e?
• CAL energy scale shift
• at PT ? 6 GeV, p-scale of CFT-only tracking
  becomes non-linear

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J/? electrons Selection Criteria (cont.)
Invariant Mass Look at Type 1 3 Combinations
with Background
Preliminary Results
J/? 1 K Sample TRK only result
M(ee)
QCD 20 GeV 8 K sample TRK only result
M(ee)

• 8K QCD_20 and 9K QCD_40 samples processed with
  p07.00.01 dØsim
• Background studies have just started
• at the moment, results a day old
• but a move forward...

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Closing Remarks

• Initial work by A. Lucotte, P. Grannis, et. al.
  provides useful benchmark for future trigger
  studies
• At all trigger levels, L1 ? L3
• L3 studies (finally) underway
• Very preliminary but tremendous progress has been
  made!
• Analysis machinery being developed
• Distribution shapes and cross-checks being done
  with Z?e?e? and Upsilon(1s) ? e?e? samples
• Large amount of work still needed...
• Future Work
• Aim for larger statistical sample
• Efficiencies and Purity studies
• Improvements in invariant mass distributions...
• Background studies QCD events
• Perform studies with SMTCFT tracks (L3 global
  tracking, d0trigsim)
• Incorporate L1 and L2 information
• will require LARGE samples

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Reference Slides
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Preshower Readout Logic

• AFE12 board -- dual threshold, charge division
  scheme
• Two-arms
• High-gain ? Low PT physics
• CP-violation, B-Physics, J/?,
• Low-gain ? High PT physics
• Higgs, Top, W/Z physics,