1. 15-Apr-15 Muon HLT Meeting C. Diez L2 Muon Trigger Status Report: L2 seeding study B. de la Cruz, C. Diez (CIEMAT, Madrid) Muon HLT Meeting 17th April, 2009 1

2. 15-Apr-15 Muon HLT Meeting C. Diez L2 seeds reminder  Parameters from L1 muon candidates converted into seeds for L2 muon reco pt estimated at interaction point global position ( ,  ) of hit at second station (MB2/ME2) firing L1  A TSOS (L2 trajectory seed) is defined at the second station with this previous info and some initial errors assigned.  Great care needed, as info is not given at the same reference system  At this point, L2 pattern recognition starts Track parameters from seed propagated to innermost reachable muon chamber Forward pattern reco: navigation outward Bacward pattern reco: navigation inward 2  ,  ptpt MB1 MB2 MB3 MB4

3. 15-Apr-15 Muon HLT Meeting C. Diez L2 Muon Trigger is already established but there may be still room for improvement optimizing the 2 step algorithm:  Pattern Recognition in the muon system and the tuning of the L2 parameters. http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=53973 http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=53973  Study the L2 Seeding  Vector values : Evaluate pt,  at IP and second station  Errors : Study L1 resolution, compared to the default errors given in the seeding Motivation for the study 3

4. 15-Apr-15 Muon HLT Meeting C. Diez  /RelValZMM/CMSSW_3_1_0_pre3_STARTUP_30X_v1/GEN-SIM-DIGI-RAW- HLTDEBUG (9000 evts) Rerun the trigger with the configuration which is implemented for CMSSW_3_1_X Tests on L2MuonSeedGenerator 4  Change L2 seed in RecoMuon/L2MuonSeedGenerator /src/L2MuonSeedGenerator.cc and check results comparing distributions of several variables (pt, eta, phi), their pulls and resolutions.RecoMuonL2MuonSeedGenerator /srcL2MuonSeedGenerator.cc

5. 15-Apr-15 Muon HLT Meeting C. Diez Comparison: variables at Vtx-MB2 SimTracks (vtx)-SimHits(MB2)  At simulated level: Compare simulated p t,  given at the interaction point and in the second station (ZMuMu sample) 5 First approx.: shift in pt by a constant ~2 GeV (CSC), ~3 GeV (DT),

6. 15-Apr-15 Muon HLT Meeting C. Diez Comparison p t Vtx-MB2 SimTracks (vtx)-SimHits(MB2) 6 No statistics for Pt > 60-70GeV Check the distributions for the available “RelValSingleMuPt1000” more bremmstrahlung losses at high Pt as expected Muon pt=1000GeV Pt vtx-MB2 vs  (at vtx) p t vtx-MB2 vs p t  (at vtx)

7. 15-Apr-15 Muon HLT Meeting C. Diez Changed pt seed: Effect in L2 distribution 7  The effect is negligible (~0.3% in pt resolution)  It doesn´t seem worthy to further parametrise the shift (for this sample ZMuMu at least) Some examples of pulls, Pt resolution after rerunning the L2 trigger with the new seeds FastStepHelix + Refit with default pt seed

8. 15-Apr-15 Muon HLT Meeting C. Diez L2 seed Errors 8 Default Errors:  Are they overstimated?  Check L1 resolution (L1 vs sim.) and take those values as seed error

9. 15-Apr-15 Muon HLT Meeting C. Diez L1 resolution 9 1.5 times smaller for CSC 2 times smaller~10 times smaller Resolution (L1-simulated) : p/pt,  Error(q/pt)=0.25 /pt (1/GeV) Error(  )=0.02 radError(  )=0.03 rad

10. 15-Apr-15 Muon HLT Meeting C. Diez Effect in L2 distributions: Pulls 10 Same number of entries Sigma changes by less 0.1%  Not seen any remarkable effect: Just to check see if this change actually affects at all, we removed the “refit” (right plots)  The effect is a bit more visible, but still not important No ReFit

11. 15-Apr-15 Muon HLT Meeting C. Diez Effect in L2 distributions: Resolution 11  Comparing resolution for the “default seeds”, changed pt and pt+new error estimation :  The resolution improves a bit for pt and , not for  with the “pt corrected”  Changing the seeds affects specially 

12. 15-Apr-15 Muon HLT Meeting C. Diez Summary  Changes in the seeding with the L2 optimizations (FastSteppingHelixPropagator (bigger extrap. steps), Refit to the L2 muon track) do not affect significantly the resolution (in pt, ,  ) nor the pulls.  The errors studied don´t seem to be “too overestimated”  For the CMSSW_3_1_X release the useful samples are only RelVal samples (ZMM, SingleMu) available, not so big statistics, relatively small pt range available  Would it make sense to use other samples where there could be more muons, not back to back, etc? Ie. Min bias or pp->mu+X? 12