Motivations for Study and Trigger Constraints Summary of Previous Studies and Work

1. 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 • 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

2. 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

3. 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 ? • 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

4. 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

5. 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: 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

6. 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

7. 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

8. 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…)

9. 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

10. 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. 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

11. For “tagged” e: MC, CAL, CAL-TRK, TRK J/ electrons — Invariant Mass 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)

12. Bin Description No. of e % of e 1 GeV 3 GeV 1 GeV 3 GeV 1 MC (all e) 2130 2130 — — 2 e matched TRK 1395 333 65.5 15.6 3 MC-TRK in CPS fid. 1130 271 53.0 12.7 4 e matched CPS551 222 25.8 10.4 5 TRK-CPS, matched CAL 551 222 25.8 10.4 6 e matched CAL 1290 330 60.5 15.5 7 TRK-CAL in CPS fid. 1025265 48.1 12.4 8 TRK-CAL, matched CPS 548 232 25.7 10.8 For “tagged” e: Initial Result on Matching Performance J/ electrons — Matching Efficiency • Very Preliminary; but a start… • Substantial improvement with CFT PT = 3  1 GeV (trigger list modification)

13. 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

14. J/ Signal: Event Selection J/ electrons — Selection Criteria & e-types (cont.) • BJ/Ks, where J/ ee: 1K sample • Most candidates are “Golden”

15. 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

16. Invariant Mass: Look at Type 1 & 3 Combinations with Background J/ electrons — Selection Criteria (cont.) 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...

17. 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

18. Reference Slides

19. 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, …