1. Electron Triggering and B-Physics at L3 (B  J/  K s, 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

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… 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

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

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/P T –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 Use MC information –identify only e  in data sample, P T  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

8. 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 z o of track as primary –under investigation… probable effect: from CAL  determination (primary vertex info…) “Tagged” e  : CFT tracks and CAL clusters   RR

9. 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 z o of tagging track as primary “Tagged” e  : CPS clusters and CAL clusters   RR

10. 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 zz    - 

11. 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 P T = 3  1 GeV (trigger list modification) M(ee) MC CAL CAL-TRK TRK

12. J/  electrons — Matching Efficiency For “tagged” e  : Initial Result on Matching Performance Very Preliminary; but a start… Substantial improvement with CFT P T = 3  1 GeV (trigger list modification) BinDescription 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 CPS 551 222 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. 1025 265 48.1 12.4 8 TRK-CAL, matched CPS 548 232 25.7 10.8

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 E T  1 GeV, |  |  2.0, E frac  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, E frac  0.95

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

15. 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 P T  6 GeV, p-scale of CFT-only tracking becomes non- linear M(ee) CAL info TRK CAL-CPS

16. 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)

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 P T physics CP-violation, B-Physics, J/ ,… –Low-gain  High P T physics Higgs, Top, W/Z physics, …