1. L2 Muon Trigger Study Status Report
B. de la Cruz , C. Diez
(CIEMAT, Madrid)
Muon HLT Meeting
20th March, 2009
20-May-18
Muon HLT Meeting C. Diez

2. Motivation for the study
L2 Muon Trigger is already established but there may be still room for improvement optimizing the 2 step algorithm:
Seeding
Pattern Recognition in the muon system and the tuning of the L2 parameters.
FirstOverview:
Where we reproduced validation histograms with official HLT Validation package (MultiTrackValidator Analyzer for residuals, pulls and efficiencies of track reconstruction) running on MC samples.
20-May-18
Muon HLT Meeting C. Diez

3. First Tests on L2MuonProducer
According to Riccardo and J.Roch, several L2 optimizations possible:
 Use of FastSteppingHelixPropagator (code implemented some time ago by Slava Krutelyov but never activated) instead of usual SteppingHelixPropagator, in the L2 pattern recognition and reconstruction (bigger extrapolation steps in L2 propagation)
 Add a final refit of the L2 muon track, considering all the final hits selected after a pattern recognition inside-out (FW) and outside-in (BW)
 In the case of Refitting, drop the outside-in (BW) pattern recognition, to save time
Use CMSSW_3_1_0_pre3 to test optimizations above and Z MonteCarlo sample:
/RelValZMM/CMSSW_3_1_0_pre3_STARTUP_30X_v1/GEN-SIM-DIGI-RAW-HLTDEBUG (9000 evts)
Results comparing distributions of several variables (pt, eta, phi), their pulls and resolutions will be shown here.
20-May-18
Muon HLT Meeting C. Diez

4. Tests on L2MuonProducer
Options presented in previous slides tested alone and in combination
Possible improvements
Usual SteppingHelix Propagator
(default config)
Fast SteppingHelix Propagator
ReFit = False
Default configuration
Test FastSteppingHelix
ReFit = True
Test Refit
Test FastSteppingHelix+ReFit
BW pattern reco = False
(ReFit = True)
Test pattern reco = False
Test FastSteppingHelix+Refit+NoBW
20-May-18
Muon HLT Meeting C. Diez

5. ReFit implemented in L2
In HLTrigger/Configuration/python/HLT_2E30_cff.py in L2MuonProducer, activate DoRefit = cms.bool( True)
adding as Parameters those from RecoMuon/StandAloneMuonProducer/python/StandAloneMuons_cfi.py
Use CMSSW_3_1_0_pre3 to test optimizations above and Z MonteCarlo sample:
/RelValZMM/CMSSW_3_1_0_pre3_STARTUP_30X_v1/GEN-SIM-DIGI-RAW-HLTDEBUG (9000 evts)
20-May-18
Muon HLT Meeting C. Diez

6. Pt distributions Comparing with Pt L1 distribution:
Removing BW pattern recognition, Pt distribution
Is still “discrete”
L1 Pt values in 2 bins: Correction shift by 2 GeV in Barrel and 3GeV in EndCaps
20-May-18
Muon HLT Meeting C. Diez

7. h distributions h only for “standard” SteppingHelixPropagator
(similar for FastStep.)
Removing BW pattern recognition affects to the values in the barrel:
Is that the expected behaviour?
No mayor differences between distributions with/ without reffiting
20-May-18
Muon HLT Meeting C. Diez

8. Pt resolution (see next slide) by 3%
Refit improves resolution
(see next slide) by 3%
No BW filter: resolution gets worse by 10% (respect to the “original” L2 reco)
Implementing the FastSteppingHelix propagator does not the resolution
20-May-18
Muon HLT Meeting C. Diez

9. Pt resolution
~20%
~31%
~17%
20-May-18
Muon HLT Meeting C. Diez

10. Pt resolution vs Pt & h
20-May-18
Muon HLT Meeting C. Diez

11. Comment on L2 vs L1
20-May-18
Muon HLT Meeting C. Diez

12. f resolution Changes in resolution smaller than in the case of Pt
Flat distributions in f in all cases (not shown)
Changes in resolution smaller than in the case of Pt
20-May-18
Muon HLT Meeting C. Diez

13. f resolution
20-May-18
Muon HLT Meeting C. Diez

14. h resolution Resolution similar in all cases
removing BW patter recogition worsens the tail of the distributions, similar peak
20-May-18
Muon HLT Meeting C. Diez

15. h resolution s~
s~ 0.005 s~
No changes with new propagator in resolution, refit doesn´t improves it
H resolution with BW pattern recognition only slightly worse (~5% difference)
20-May-18
Muon HLT Meeting C. Diez

16. Pull distributions s~ 2.2 s~ 2.3 s~ 1.4 s~ 1.9 s~ 1.1 s~ 2.1 s~ 1.1
mean
-0.09
-0.03
~ -0.18
s~ -0.09
s~ 0.45
20-May-18
Muon HLT Meeting C. Diez

17. Pull distributions s~ 1.05 s~ 2.07 s~ 1.03 s~ 2.20 s~ 0.95 s~ 1.40
20-May-18
Muon HLT Meeting C. Diez

18. Sigma :Pull distributions vs h
Pulls do not change with the FastStepping Helix Propagator
Flatter distributions with Refit for distributions as a function of h
20-May-18
Muon HLT Meeting C. Diez

19. Pull distributions vs h
Pulls do not change with the FastStepping Helix Propagator
Flatter distributions with Refit for distributions as a function of h
20-May-18
Muon HLT Meeting C. Diez

20. Comments & Outlook
The improvement on the “SteppingHelixPropagator ” does not worsen the resolution
Compare these set of validation plots to existing ones in (Jeff. Klukas).
The work will go on, paying attention to the different L2 parameters being used
20-May-18
Muon HLT Meeting C. Diez