# Presentation: 803353

## Electron Triggering and B-Physics at L3(BJ/Ks, where J/ ee)Abid Patwa, André Turcot, and Sailesh ChopraB-id Vertical ReviewDØ, FermilabWednesday, April 4, 2001 

- 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

- AGENDA

## 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...

- 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

**Necessary to understand trigger resolution **
**and efficiencies for all of the above issues**

## Summary of Trigger Studieswith 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 ?
- Recently started using tsim_l1 and l2, dØtrigsim
- Progressing...
- Studies at L3:  (Patwa, Turcot, Chopra)
- Also recently started, progressing well
- will outline general scope here

## 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**

## Sample:
processed under dØsim p07.00.03
J/ ee, 1000 events total   (two 0.5K files)
Event selected: pythia+QQ;   PT (B)  3.0 GeV
at least 2 electrons with PT (e)  1.0 GeV,  ||  2.5 
Avg. min. bias overlay:  |NMB|=1.1,  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

Study concentrates on L3 output: 
e+/e-: TRKing, CPS, and CAL information
RootTuples, variable definitions:
some L3 variables straightforward to understand;  other variable descriptions difficult  must look at code to understand; little documentation
see http://www-d0.fnal.gov/~abid/b_id_studies.html
L3 Tracking: CFT only  

- processed under dØsim p07.00.03
- J/ ee, 1000 events total   (two 0.5K files)
- Event selected: pythia+QQ;   PT (B)  3.0 GeV
- at least 2 electrons with PT (e)  1.0 GeV,  ||  2.5
- Avg. min. bias overlay:  |NMB|=1.1,  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
- Study concentrates on L3 output:
- e+/e-: TRKing, CPS, and CAL information
- RootTuples, variable definitions:
- some L3 variables straightforward to understand;  other variable descriptions difficult  must look at code to understand; little documentation
- see http://www-d0.fnal.gov/~abid/b_id_studies.html
- L3 Tracking: CFT only

- L3 Electron Studies: J/ee (cont.)

## 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(),   = track’s 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
- CPS
- a.) Form Single Layer Clusters (SLCs): cycle through hit CPS
-      strips, ganging adjacent hit strips into clusters.
- b.) Form 3D clusters -- matching hits in all three layers.
- L3DEncps -- Number of CPS clusters
- L3DECpsN1, N2, N3 -- Number of CPS strips above threshold in CPS layers 1, 2, 3
- L3DECpsE1, E2, E3, -- CPS-SLC energy in CPS layers 1, 2, 3
- L3DECpsE -- CPS 3D cluster energy (E1+E2+E3)
- L3DECpsPhi -- CPS Phi
- L3DECpsZ -- CPS hit z-position
- L3DECpsChic2 -- CPS 2
- L3DECpsRes -- CPS hit residuals

## L3 J/ Studies: Matching Resolution

- L3 J/ Studies: Matching Resolution

- 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

**Comparison: MC electrons with tracks (TRK) and CAL**

****

****

****

****

- CAL-MC			             TRK-MC

- CAL-MC			             TRK-MC

## J/ electrons — Matching Resolution: TRK-CAL

- J/ electrons — Matching Resolution: TRK-CAL

- 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...)

**“****Tagged” e********: CFT tracks and CAL clusters**** **

****

****

****

******R**

****

## J/ electrons — Matching Resolution: CPS-CAL

- J/ electrons — Matching Resolution: CPS-CAL

- 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

**“****Tagged” e********: CPS clusters and CAL clusters**** **

****

****

****

******R**

****

## J/ electrons — Matching Resolution: CFT-CPS

- J/ electrons — Matching Resolution: CFT-CPS

- 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. Turcot’s 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

**“****Tagged” e********: CFT tracks with CPS clusters**** **

- z

- z

****

****

****** ******** ****-******** **

## J/ electrons — Invariant Mass

- J/ electrons — Invariant Mass

- Calculation based on:

**For “tagged” e********: MC, CAL, CAL-TRK, TRK**** **

- M(ee)

- 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)

- M(ee)

- M(ee)

- M(ee)

- MC			                CAL

- CAL-TRK			                TRK

## 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)

## 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
- Apply cuts for each:
- Type 1: TRK-CPS: |z|  20 mm, ||  12 mrad
- Type 3: TRK-CAL: ||  50 mrad, Efrac  0.95

## J/ electrons — Selection Criteria & e-types (cont.)

- J/ electrons — Selection Criteria & e-types (cont.)

- BJ/Ks, where J/ ee:   1K sample
- Most candidates are “Golden”

**J/******** Signal: Event Selection**

## J/ electrons — Selection Criteria (cont.)

- J/ electrons — Selection Criteria (cont.)

- Calculation based on:

**Invariant Mass: electron selection criteria applied**

- M(ee)

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

- M(ee)

- M(ee)

-     CAL info			                TRK

- CAL-CPS

## J/ electrons — Selection Criteria (cont.)

- J/ electrons — Selection Criteria (cont.)

- 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...

**Invariant Mass: Look at Type 1 & 3 Combinations **
**with Background**

- M(ee)

**Preliminary Results**

- J/
- 1 K Sample
- TRK only
- result

- QCD
- 20 GeV
- 8 K sample
- TRK only
- result

- M(ee)

## 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 SMT+CFT tracks (L3 global tracking, d0trigsim)
- Incorporate L1 and L2 information...
- will require LARGE samples

## Reference Slides

## 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, ...