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Update On Jet Energy Corrections

Update On Jet Energy Corrections. Robert M. Harris Fermilab Physics / Trigger Week October 26, 2007. Outline. MC Jet Correction Factorization Plan and Status Developments in Factorized Corrections Zero Suppression Correction Response vs. P T for g + jet events.

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Update On Jet Energy Corrections

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  1. Update On Jet Energy Corrections Robert M. Harris Fermilab Physics / Trigger Week October 26, 2007

  2. Outline • MC Jet Correction • Factorization Plan and Status • Developments in Factorized Corrections • Zero Suppression Correction • Response vs. PT for g + jet events. • Jet Correction Methodologies • Developments in Monolithic Corrections • Quark Jet Correction Studies • Global Fit Investigation • Conclusions Discussing status and all updates shown to JetMET And JESTF since September 15-21 CMS Week For discussion of developments in the top quark group please see talk by J. D’Hondt yesterday and CMS-AN 2007 / 029 Robert Harris, Fermilab

  3. FORWARD ENDCAP BARREL 4 < |h| < 4.4 2.295 < |h| < 2.487 |h| < 0.226 MC Jet Corrections for CMSSW_1_5_2Kostas Kousouris (JetMET Meet Oct. 4) • Standard corrections from MC truth released October 6 • For Midpoint Cone R=0.5, 0.7, Iterative Cone R=0.5, 0.7, KT D=0.6 • Official support expected soon for KT D=0.4, Seedless Cone R=0.5, 0.7 • Un-official version of these corrections have been supplied to the experts. • Similar correction as Spring07 in barrel and endcap • Smaller correction than Spring07 in forward which has improved response. • Asymmetric HF response vs. h at low PT is not corrected. Robert Harris, Fermilab

  4. Factorization Plan • Factorized jet corrections will replace MC Jet Corrections in CMSSW Postdocs in JES Task Force Jochen Cammin (Rochester) L5 Flavour Corrections Selda Esen (Brown) L4 EMF Corrections Kostas Kousouris (Fermilab) L2 h & L3 PT corrections • Breaks correction into natural pieces. • Found in stages of time & precision A. MC truth (now) B. Data-driven techniques using MC (soon) C. Data-driven using actual in-situ data (’08) D. Eventually back to MC tuned on data. • Factorized corrections are work of the Jet Energy Scale Task Force in JetMET • Especially the hard working postdocs ! Robert Harris, Fermilab

  5. Factorization Status • L1 (offset): 1st pass Zero Suppression correction done including code to use it. • Need pile-up component of correction next. • L2 (h): MC truth h dependence correction almost done. • No correction code yet. • 1st study of dijet balance for data-driven phase of correction done. • L3 (pT): MC truth pT dependence correction almost done. • No correction code yet. • Study of g + jet balance for data-driven phase of correction begun. • L4 (EMF): MC truth EMF dependence factorization almost done • Study showing feasibility for limited range of pT and h completed, and work ongoing. • L5 (flavour): MC truth flavour dependence study ongoing. • L6 (UE): No developments • L7 (parton): No developments but we have a volunteer. Robert Harris, Fermilab

  6. Zero Suppression CorrectionOlga Kodolova (JetMET meet Oct. 4) • Adds back jet energy lost due to calorimeter thresholds that suppress noise • Significant correction: 25% for 20 GeV CaloJet in Barrel • Correction decreases with ET, and has complex h dependence ( ↑ h<2, ↓ h>2) • Correction restores jets to there measured vales w/o thresholds. • 1st Zero Suppression Correction completed and available now in CMSSW • Special CMSSW_1_3_4 sample w/o HCAL cell level ZSP or Ecal Selective Readout. Jet Response & Closure Test vs. ET Fractional Correction vs. ET and h Jets After Corrections = Jets w/o Thresholds Jets Before Corrections Robert Harris, Fermilab

  7. Jet Response vs. PT from g + Jet EventsAnwar Bhatti (JES Task Force Oct. 2) • g + Jet PT balance or MPF provide jet response vs. PT in barrel • High rate calibration process, but lots of subtle issues need study. • MPF response a little higher than PT bal. at most PT (radiation?). • Response to GenJet a little larger than PT bal. (particle vs. parton ?). • PT bal. response a little higher than dijet system response (q vs. g?). • Also prior work by O. Kodolova et al and J. Cammin g Jet Jet Response Jet Response Photon PT (GeV) Photon PT (GeV) Robert Harris, Fermilab

  8. < CorCalo PT – Gen PT > < CorCalo PT > Jet Correction MethodologiesKostas Kousouris (JetMET Oct. 18) • Four methodologies explored for finding correction vs. pT in barrel. • Binning in GenJet or CaloJet pT, measuring response with ratio or difference. • Using QCD sample w/o weights (“flat” spectrum) and with weights (QCD spectrum). • “MC Jet Method”: bin in GenJet pT and measure CaloJet pT / GenJet pT • Answers “What is response of GenJet?” independent of input spectrum. • “CaloJet Method”: bin in CaloJet pT and measure CaloJet pT - GenJet pT • Answers “What GenJet pT gave my CaloJet pT?” which depends on input spectrum. • CaloJet method closes better vs corrected CaloJet pT. • Similar to work of S. Esen, G. Landsberg and P. Schieferdecker. Discussion ongoing. Spectrum Dependence Correction from Methods CaloJet Closure Test Correction Correction MC Jet Method No Weights MC Jet Method CaloJet Method No Weights CaloJet Method Corrected CaloJet PT (GeV) CaloJet PT (GeV) CaloJet PT (GeV) Robert Harris, Fermilab

  9. Quark Jet Correction Studies • Quark jet corrections Loïc Quertenmont, Dorian Kcira, Giacomo Bruno (JetMET Oct. 4) • MC Jet overcorrects W from top • Because MC Jet for mixture of q + g ? • Because of closure issues in MC jet ? • Quark jet correction found from Z sample • Private monolithic correction. • Reconstructs correct W mass. Quark Jet Corr. No Corr. MC Jet Corr. • g + jet corrections applied to qqH Efe Yazgan and Alexandre Nikitenko (JetMET Oct. 4) • Jet corrections derived from g + jet sample in CMSSW ala ORCA method. • Overcorrects qqH jets at high h because of large amounts of gluons at high h in the g + jet sample. g + Jet Corr. MC Jet Corr. No Corr. Maiko Takahashi Robert Harris, Fermilab

  10. Global Fit for Hcal/Jet CalibrationChristian Autermann(JetMET Oct. 18) • Trial exploration of framework to combine all factors and perform global fit. • Work of C. Autermann, C. Sander, P. Schleper, H. Stadie, R. Wolf at Hamburg. • Test of the tools: calibration of jets and of all 2048 CaloTowers. • Use g + jet sample and form c2 • Between the g energy and corrected jet energy in 110K back-to-back clean events. • Between the track momentum and corrected tower energy in 1.5K g+jet events • Minimize the c2 to find the correction function for each CaloTower and Jet. Jet Resolution Jet Response Tower K-factor per event Robert Harris, Fermilab

  11. Summary & Note • MC Jet corrections available for 1_5_2 • Factorized corrections will replace it soon. • 1st Zero Suppression correction available. • g + jet studies begun for correction vs. jet pT in barrel. • Jet correction methodologies for the factorized correction being actively studied and discussed • Work on monolithic corrections continues to teach us valuable lessons. • We are working on completing a draft of our JES note for December CMS week. • 90% done: 28 pages, 24 plots. • Needs little more work and editing. Robert Harris, Fermilab

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