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Electron Isolation & Trigger Studies from W+jets

Electron Isolation & Trigger Studies from W+jets. History: old results using 11.0.x simulated W+jets events (filtered or Susy studies) New 12.0.6 results using newly generated W+jets events (filtered for SM physics) Simulation done using Alpgen/Jimmy for W( e) +0,1,2,3,4,5 partons

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Electron Isolation & Trigger Studies from W+jets

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  1. Electron Isolation & Trigger Studies from W+jets • History: old results using 11.0.x simulated W+jets events (filtered or Susy studies) • New 12.0.6 results using newly generated W+jets events (filtered for SM physics) • Simulation done using Alpgen/Jimmy for W(e)+0,1,2,3,4,5 partons • Old prod with parton level filter for Susy • 4 jets with pt > 40 GeV • leading jet with pt > 80 GeV • MissEt > 80 GeV • New prod with parton level filter for SM • for electrons ask for one region of =0.120.12 with ET>10GeV in ||<2.7 M. Wielers (RAL)

  2. Old trigger and offline efficiencies • ss M. Wielers (RAL)

  3. Look at L1 distributions for events acc/failing L1 cuts • Rejected events typically have larger ET and suffer from isolation • accept if ET(clus) > 18 GeV, EMIsol  3 GeV, HDCore  2 GeV, HDIsol  2 GeV • Most events fail EMIsol cut M. Wielers (RAL)

  4. Look at L2 distributions for events acc/failing L1 cuts • Just longer tails, but otherwise rejected events look like ‘good’ electrons • Rejected events: composition of electrons within jets + jet a bit away from EM cluster • As Susy filtered events are more ‘busy’ than SM filtered events, let’s do the same now with new samples M. Wielers (RAL)

  5. SM filtered W(e)+jets events • Use newly generated W+jets events • Simulated with 12.0.6.4 with correct range cut of 30 microns • Reconstructed with 12.0.6.4 • W+0, 1, 2, 3, 4, 5 partons available (DS 6101-6106) • From AODs produce customised AAN’s produced • prepared by Alessandro from AOD’s (first test version) and to be used by the W+jets sub-group • Stat per datasets 50k, which has 10K, ~30-45k of events used (prod was still running), W+Np5 has 10K stat • Looked at W+1, 2, 3, 4, 5 partons, not W+0p because of problem at generation level (being looked at). Also similar problem but much less pronounced in W+2 and 4p. • For contents, see http://indico.cern.ch/conferenceDisplay.py?confId=17167 • Reconstruction done via Panda at BNL (where events were produced) M. Wielers (RAL)

  6. Reconstruction via Panda • Just in same directory as where you run from (but under your workarea for given release) • Instead of • athena AnalysisSkeleton_topOptions.py • type • pathena AnalysisSkeleton_topOptions.py –inDS trig1_misal1_mc12.005802.JF17_pythia_jet_filter.recon.AOD.v12000604_tid008650 --outDS user.monikawielers. AANT_misal1_mc12.005802.JF17_pythia_jet_filter.v1200064_tid008650 –nJobsPerFile 20 • inDS: input dataset • outDS: output DS, note has to start with your grid name, e.g. user.monikawielers. • --nFilesPerJob: number of files to be chained per job • --split 5: create 5 sub-jobs • -c "EvtMax=50000“ • --site ANALY_LYON | run in Lyon • Panda can be used to run at BNL or Lyon, if DS not available the job will tell you at the end of the submission M. Wielers (RAL)

  7. Reconstruction via Panda • Once your first job finished you can monitor your job from your ‘private’ Panda web page, called similar to • http://gridui02.usatlas.bnl.gov:25880/server/pandamon/query?ui=user&name=monika%20wielers • Alternatively for monitoring in window • pathena_util • show() : show jobs • status(3) : shows status of job 3 • kill(3) : kill job number 3 • Once job finished it’s automatically registered to Grid and can be found in directory as specified by outDS • In there you have ntuples, histos, log file • can be retrieved as usual via dq2 • Panda can also run on nightlies at BNL! • More info an how to use panda • https://twiki.cern.ch/twiki/bin/view/Atlas/DAonPanda M. Wielers (RAL)

  8. Trigger efficiencies for W+jets e+jets • Normalise eff. to events which pass following kine. cuts • ET(ele) > 25GeV, ||<2.45, and not in b/ec crack (1.37 < || < 1.52) • Remember 12.0.6 trigger selection not well optimised, should be done with updated hypos • As seen in the past slow decrease in efficiency with increase of the number of jets. • Compare with drop from incl. W to W+5 jets of 25% in Susy filtered W+jets events • Now drop of ‘only’ ~7% seen M. Wielers (RAL)

  9. offline efficiencies for W+jets e+jets • Compare loose, medium and tight IsEM • https://twiki.cern.ch/twiki/bin/view/Atlas/EgammaATLASRecoPerformance#Baseline • Loose: no calo strip cuts, track match +loose cuts on E/p (clus-track) and (clus-track) (isem & 0xFF) • Medium: + strips, track quality (isem &0x3FF) • Tight: + TRT cuts (isem) • We need to figure out which type of id is best for these samples, my guess is medium • Drop in eff of few% • To be compared to 7% by trigger selection • Drop smaller than trigger as no explicit isolation is required, it’s the EM isolation cut which typically fails M. Wielers (RAL)

  10. More on isolation • look at distance of electrons to nearest reconstructed jet (Cone R=0.4) • Isolated electrons and nearest jet should coincide • The more partons the higher the prob. one of the jets too near to electron M. Wielers (RAL)

  11. Electron Isolation (cont) Isolation ET for medium identified electrons plus after trigger • Hard to measure non-isolated electrons… • Won’t show up in eff extraction using Zee as one ele in jet • Try to get an idea of ‘degree’ of non-isolation e.g. look at ET in iso. cone • Looking at R=0.4 shows clear diff. question is • still visible if we add bckgd ? • How to extrapolate ? M. Wielers (RAL)

  12. Conclusions and Outlook • Fist look at trigger efficiencies in W+jet events • Loss in trigger eff ~7% higher in W+5p w.r.t. W+1p events • Effect much smaller than seen in ‘old’ files filtered for Susy background studies • Offline loss would be few % • Nothing much to worry about any more • To avoid loss of trigger eff due to isolation look at alternative triggers e+ETmiss/jets • Note, at start-up we don’t plan to run with isolation for e-cand, such triggers are needed once lumi is higher • To get an idea on isolation one can try to look in isolation cones around identified electrons • Will be tough to deduce efficiency loss • Still needs to be looked at to ensure ‘reality matches MC’ M. Wielers (RAL)

  13. Backup M. Wielers (RAL)

  14. Some distributions • Look at events with ‘good’ offline electron (reco electron in ||<2.45, and not in b/ec crack (1.37 < || < 1.52), use medium IsEM cuts + e25i trigger M. Wielers (RAL)

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