1. 1  trigger optimization in CMS Tracker Giuseppe Bagliesi On behalf of  tracking group Workshop on B/tau Physics at LHC Helsinki, May 30 - June 1, 2002

2. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 2 Outline HLT Pxl and Tk results with 3+2 and 2+1 pixel layout. CPU performances for Pxl and Tk Charged Higgs with Tracker Off Line Tau tagging: Preliminary studies on mass reconstruction

3. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 3 High Level Trigger Low luminosity: 2x10 33 cm -2 sec -1 ORCA 4_5_4, CMSIM 120 Reading the DB with ORCA_5_3_4 gg  (bb) A/H(200,500)  (bb)  2  jets+X Final Goal is to achive a rejection factor ~ 1000 after L1 gb  t H    jet + 3Jets Final Goal is to achieve a rejection factor  30 after L1 and Missing E T cut. PRELIMINARY RESULTS! High Luminosity: 10 34 cm -2 sec -1 ORCA 6_1_0

4. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 4 A. Nikitenko

5. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 5 Isolation Algorithms Signal vertex identified by: Pxl: leading track (P T >3GeV) Trk: best signal vertex candidate from pixel reconstruction. signal vertex leading track jet axis jet matching cone  R = 0.1 signal cone reg Tk cone isolation cone Pxl: use pixel lines (i.e. tracks reconstructed only with pixel layers). Trk: use regional tracker reconstruction. Both algorithms count number of tracks inside signal (N SIG ) cone and isolation cone (N ISO ). Events is accepted if leading track exists and N SIG = N ISO

6. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 6 A. Nikitenko

7. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 7 A. Nikitenko

8. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 8 ORCA 6_1_0: Pixel isolation (I) H(500GeV) -> 2  ->jets first jet is OK, small drop in efficiency due to more pxl. ineff. put in orca6. Second jet is OK for low lumi. Why it’s so bad for high lumi ? it’s due to way of finding 2- nd jet at Lvl- 2. Sasha is tuning the L2 cuts for high Lumi A. Nikitenko

9. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 9 ORCA_6_1_0: pixel isolation (II) QCD background (P T : 50-80 GeV) degradation of the rejection for qcd background due to the same reasons as for the signal A. Nikitenko

10. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 10 A. Nikitenko

11. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 11 A. Nikitenko

12. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 12 A. Nikitenko

13. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 13 H ->  HLT with full track reconstruction A “must”: decrease CPU time… First approach: Reconstruct tracks only around a region of interest: regional tracking with a DetUnit filter Second approach: seed selection in the region of interest Conditional Track Finder: stop trajectory builder @ 6 hits Selection much faster than with regional tracking, but loose ~5% signal efficiency and decrease bkg rejection of ~ 10 % Next approach (in progress…) NewSeedGenerator “regional” Optimization of the ROI… Fast (optimized) track finder (ORCA_6_1_1)

14. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 14 CMS IN-2001/045 A similar approach should be used for the regional seeding

15. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 15 H(500GeV) -> 2  ->jets with tracker (ORCA_6_1_0) Comparison with Calo+Pxl (Low Lumi) Similar Performances

16. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 16 H(500GeV) -> 2  ->jets with tracker (ORCA_6_1_0) Comparison with Calo+Pxl (High Lumi) Similar Performances

17. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 17 H  2   2 Jets Selection with Tracker: performances (low luminosity) (ORCA_5) Full/Staged Pixel scenario comparison 3+22+1

18. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 18 How to reduce tracking time in the isolation algorithm R M =0.1 R SIG =0.065 R ISO =0.45 R REG = 0.45 Jet LT Reconstruct tracks inside R M only Find LT: If LT doesn’t exists stop everything If LT exists apply isolation on rec Tk, if it is not isolated stop everything If event is isolated go on reconstructing also tracks inside region between R M and R REG Apply isolation to all tracks. Depending on bkg sample and pixel staged scenario a CPU time reduction varying from 20% to 40% is obtained

19. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 19 Track reconstruction time Low luminosity (ORCA_5) Tracker Reconstruction steps (for single jet) :Time (sec) 3+2/2+1 (1 GHz cpu) BkgmH 200mH 500 Pxl Reco0.0700.0640.060 Trk Reco 1 st Jet0.1250.0560.050 Isolation for 1 st jet<0.005 Total Time0.200/0.2160.125/0.1360.115/0.126

20. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 20 H +  j Selection with Tracker (I) Low luminosity: 2x10 33 cm -2 sec -1 3+2 pixels scenario (preliminary 2+1) Higgs mass = 200, 400 GeV/c 2 L1 Calo = 1  -jet, E T > 80 GeV L2 = Missing E T (MET) + L2 Tk: MET > 80 GeV L2 Tk: isolation + hard pt cut on leading track Final Goal is a bkg rejection  30 after MET cut. Preliminary results at 10 34 cm -2 sec -1

21. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 21 MET and isolation cut correlation Missing E T cut and L2Tk selection are almost uncorrelated To increase statistics no MET cut has been applied on plots. QCD background H + -> 

22. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 22 H +  j Selection with Tracker (II) (3+2 Pxl) (ORCA_5) NTk = 1.OR.3 0.50 R M =0.1, R S =0.065, R I =0.4 PTLTCUT = 1. – 25. GeV R M =0.1, R S =0.065, R I =0.4 PTLTCUT = 1. – 25. GeV

23. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 23 H +/- ->  ->jet with tracker (ORCA_6_1_0) N trk =1,3 NO MET cut, Low Lumi ORCA_5 best result S. Gennai

24. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 24 H +  j Selection with Tracker (III) 3+2 Pxl and 2+1 Pxl comparison (ORCA_5) R M =0.1, R S =0.065, R I =0.4 PTLTCUT = 1. – 25. GeV R M =0.1, R S =0.065, R I =0.4 PTLTCUT = 1. – 25. GeV Staged Scenario 2+1 3+2

25. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 25 H +/- ->  ->jet with tracker (ORCA_6_1_0) NO MET cut, High Lumi N trk =1,3 S. Gennai Performances similar to Low Lumi

26. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 26 H +  j Selection with Tracker Cumulative distribution L2Tk working point: R M =0.1, R S =0.065, R I =0.4 P T LeadTk > 20. GeV QCD bkg rate versus Jet E t

27. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 27 Off Line tau tagging Preliminary studies on reconstructed tau mass in hadronic tau decays To do: ORCA_6_1_0 (in progress…) Combination with vertex reconstruction   reconstruction

28. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 28 Preliminary results on tau mass tag ORCA_6_1_0 events passing LVL1 selection Arbitrary units (normalization on number of entries) At least one (or three) tracks in the reconstruction cone  0 are taken from MC truth. R<0.4 around the jet direction Et > 1 GeV S. Dutta Ntk>0 Ntk>2

29. 31/5/2002 G. Bagliesi – bTau workshop – Helsinki 30/5–1/6 29 Conclusions H->  ->jets   45% (30% with ORCA_6???) efficiency with ~2x10 3 QCD rejection is achievable at L2 (both with Calo + Pxl and Trk + Pxl) 3+2 Vs 2+1 scenario: Pxl can get the same efficiency and bkg rejection using also L2Calo Trk has decrease in efficiency of ~ 10% (@ the same Bkg Rate) Charged Higgs (L2TK isolation) Signal Eff. ~ 50 % with Bkg Rej ~ 30 Timing (low luminosity): Pxl can identify taus in less 50 msec Tk can identify single tau in ~192 msec (Single  with hard P T cut) Work in progress … High luminosity Timing Performances Off Line Tagging (mass + vertex tag)