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Standard Model Photonic Final State Analyses in CMS: 1fb-1 and Beyond

This paper discusses the standard model photonic final state analyses in CMS, including integrated luminosity/event yield forecasts, Tevatron results, vertical integration, CMS ECAL and calibration status, electromagnetic object commissioning with first collision data, and major analysis results.

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Standard Model Photonic Final State Analyses in CMS: 1fb-1 and Beyond

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  1. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Standard Model Photonic Final States: 1fb-1 and Beyond S. Gascon-Shotkin (IPN Lyon/UCBL 1) CMS Physics France, 1 Avril 2010 g + b

  2. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Outline I. Standard Model Photonic Final State Analyses and the CMS “QCD Photons” Group II. Integrated Luminosity/Event Yield forecasts, Tevatron results III. Vertical Integration (ECAL DPG  e/g POG QCD gHgg) IV. The CMS ECAL and Calibration Status V. Electromagnetic Object commissioning with first collision data VI. Status of “first” (~1pb-1) major analysis: Inclusive isolated g differential cross-section VII. “Later” (~10pb-11fb-1) analyses: g + jets, g + b and gg + X VIII. Common theory issues IX. Conclusion

  3. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 I. The QCD Photon Group and Analyses PTDRII: No QCD Photon Activity/Studies Post-PTDRII: CMS NOTE 2007/004 (P. Gupta et al.) , g + jets then start of a working group (2008). Plan of work and mission:

  4. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 I. The QCD Photon Group and Analyses • Caltech: A. Bornheim, M. Gataullin, V. Litvine, Y. Ma • CEA-Saclay: S. Ganjour, L. Millischer, F. Ferri, J. Malcles • CERN: T. Orimoto • Delhi University: S. Ahuja, S. Bhattacharya, S. Chauhan, B. Choudhary, S. Jain, S. Jain • Fermilab: V. Chetluru • Florida International University: V. Gaultney, S. Linn • IHEP/Beijing: J.-Q. Tao, H. Xiao • LIP: A.David,M.Gallinaro, P.Musella,J.Varela • Lyon: S. Gascon-Shotkin, N. Chanon, M. Lethuillier • Middle East Technical University: M. A. Guler, K. Ocalan, E. Yildirim • University of Minnesota: A. De Benedetti • MIT: Y Kim, Y.-J. Lee, G. Roland, W. Busza, B. Wyslouch, Y. Yilmaz • National Central University: S.-S. E. Yu, Y.-J. Lu, D. Mekterovic, C.-M. Kuo • National Taiwan University: R.-S. Lu • Notre Dame: T. Kolberg, N. Marinelli • Rutgers: O. Atramentov, Y. Gershtein • UC San Diego: M. Pieri • University of Virginia: C.-Z. Lin, B. Hirosky, C. Neu • Wisconsin: M. B. Anderson, S. Dasu

  5. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 II. Integrated Lumi/Event Yield forecast Take 1 and 10pb-1 as ICHEP scenarios g + X: only analysis with a chance at sufficient statistics for ICHEP. May request approval for spectra from other analyses

  6. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 II. Tevatron Results

  7. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 II. Tevatron Results

  8. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 III. “Vertical Integration” ECAL DPG  e/g POG QCD gHgg (calibration) (object comm.) Hi-pt/Exo g Centralised/coordinated MC requests since FALL 08 Agreement for common skim for 7 TeV Participation in PAS EGM-10-001 “Electromagnetic physics object commissioning with first LHC data” (900-2360 GeV) Provide HO background estimates and kinematics to Hgg (see S. GANJOUR talk)

  9. IV. CMS ECAL and Its Calibration Our PWO crystal electromagnetic calorimeter is the first high-precision ECAL at a hadron collider Barrel: || < 1.48 36 Super Modules 61200 crystals Two Endcaps: 1.48 < || < 3.0 4 Dee’s 14648 crystals Long-term calibration (and monitoring) goal: attain and maintain in situ the design energy resolution of 0.5% (as achieved in test beams). Crucial for Higgs searches. This year: starting with a ~1.5% precalibration precision in the barrel achieve ~1-2% stable calibration precision that would be suitable for early physics, e.g. with Z and W decays.  Marat Gataullin (CMS Collaboration)

  10. IV.First Diphoton Resonance in CMS Good agreement with the expectations, especially for the width, rates, and S/B. First intercalibration of the SuperModule scales was performed (see Tiziano’s talk given March 15). The performance of the calibration stream (AlCa) is also consistent with the expectations. T. Camporesi Commissioning Talk CMSWeek Plenary 15mar10 Data Simulation Marat Gataullin (CMS Collaboration) 10

  11. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 V. Electromagnetic Object commissioning Participation of many QCD g members in PAS EGM-10-001 (and related ANs) Nsc/event NbasicCluster/SC Plane 1 Corrected Et Barrel Photon Et Barrel Preshower Plane 1

  12. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 V. Electromagnetic Object commissioning Participation in PAS EGM-10-001 (and related ANs) Tracker Hollow Cone Isolation h width Barrel HCAL Isolation ECAL Isolation Barrel

  13. Ingredients of X-section Measurment Nobserved number of observed candidates in data P photon purity (combination of MC and data) U unfolding factor for efficiency, energy scale, energy resolution (MC initially, correction with electron data later) L total integrated luminosity

  14. Data Flow Primary Dataset ? Depends on PhysCoord/AnaOps Secondary data-set Central Skim Transfer SD/Skim Tier-2 MultiPhotonAnalyzer Filter modules for Run/LS/Event Selection and Object cleaning

  15. Data Quality • Active with the PVT group in data and MC validation + Close contact with Photon DQM/Offline • Data and MC comparison • Event selection and object cleaning • MET studies for background rejection • Monitor output of run-dependence tools M. Anderson (PVT Code) T. Kolberg, N. Marinelli (Photon OfflineDQM Code)

  16. DATA signal background Isolation VI.Status of g + jets Analysis: How to Measure Purity: Two Methods 2-bin Technique Find a selection which maximizes the difference between signal and background efficiencies Template Fitting CDF

  17. VI.Template Studies from 10 TeV MC • Discriminant • sigma eta-eta • combination of ecal, hcal, track isolation, H/E, E2x5/E5x5 • combined ecal, hcal, track isolation • conversion track p/photon candidate E • Expect to have updates with 7 TeV MC in one of the next QCD photon meetings V. Gaultney M. Anderson L. Millischer T. Kolberg, N. Marinelli

  18. VI.Input from Wγ Cross-Section P. Musella Good agreement between MC truth and fitting method

  19. VI. Efficiencies Studies • Skim efficiency • Trigger efficiency • MC efficiency for ICHEP • See figures for the Pythia MC studies • Data-driven efficiency (once enough Z electrons are accumulated) (10 TeV) S. Ahuja

  20. VI. Examples of 7 TeV MC Efficiency Studies • Compared 7 TeV Madgraph and Pythia γ+jets • Integrating with common tools • Will produce efficiency with the same pt and eta binning as those for the final cross section measurement D. Mekterovic The drop of Madgraph efficiencies below 40 GeV is due to a lack of MC samples with Ht < 40 GeV.

  21. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VI. First data-driven Efficiencies and Energy Scale

  22. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VII. Later analyses: g + jets, g + bjets g + jets (~10pb-1) 1) Use Anti-kt 5 Calo-jets  (Cross-check with PF jets)2) Use the same template and efficiency tools as for inclusive photons g + b jets(~10pb-1) 1)  work closely with the inclusive photon and photon + jet groups for     photon purity and jet related systematics2) estimate non-b fraction by fitting the secondary vertex mass3)   inclusive x-section with ~10/pb of data     differential x-section once hundreds of /pb are accumulated

  23. VIII.Higher order  Generator Studies Generators of +X processes BOX BORN ONE FRAG TWO FRAG DIRECT FRAGMENTATION

  24. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VII. “Later” Analyses: gg + X gg + X: Cutbased selection/templates (also see L. MILLISCHER talk) Y. Ma et al 7 TeV 10 TeV, similar isolation cuts S. Ganjour et al

  25. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VII. “Later analyses” : gg + X gg + X: g/p0 discrimination technique (ANN) After preselection similar to that of cut-based analysis: Two categories of variables used as input for TMVA : - Cluster shape variables : cPP, R9, SigmaPhi, E3x3/(E3x3-E1st-E2nd)‏ - Environment variables : Pt_phot/Pt_jet, dR(photon, closest SC), dR(photon, closest track)‏ N. Chanon, J. Tao et al Cut on both photons 1) Cluster shape Nnoutput1>0.927 2) Environment NNoutput2>0.847 S=99.42 EffS=0.46 RejB=0.91 Purity>80% and best signal efficiency, M>40 GeV

  26. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VIII. Outstanding theory questions Higher-Order Kinematics/reweighting Isolation cone issues (relevant for all analyses) New theoretical approaches and Data comparison (Sherpa...)

  27. VIII. Higher order  Generator Studies Generators of +X processes GAMMA2MC, NLO Bern, Dixon, Schmidt, hep-ph/0211216, 2002 RESBOS Balazs, Berger, Mrenna, Yuan, hep-ph/9712471, 1997 DIPHOX Binoth, Guillet, Pilon, Werlen, hep-ph/9911340, 2000 FIXED ORDER : NLO NLO with NNLL Resummation FIXED ORDER : NLO BORN + FRAG (and NLO corrections)‏ BOX (and NLO corrections)‏ Resbos only 1-frag : - LO, effectively in Resbos - NLO in Diphox 2-frag : DIPHOX only (NLO)‏

  28. VIII. Higher order  Generator Studies K-factors for Born + Frag processes : 1 Dim N. Chanon et al K-factors far to be flat !

  29. VIII. Higher order  Generator Studies K-factors for Born + Frag processes : 2-Dim K-factor RESBOS / Pythia Born K-factor DIPHOX / Pythia Born M M M M qT qT Pythia phase space is under populated ! - For large qT, K-factor is null because there is no Pythia event ! - Looking for Madgraph sample (ME-PS matching allows harder spectra)‏

  30. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 IX. Conclusion Well-established plan of work for ICHEP principal targeted analysis (inclusive gamma) with responsibilities assigned Work in progress to well-advanced on other lower-rate analyses ( gamma + jets, Gamma gamma + x…gamma + b)..

  31. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 VII. Remerciements Jean-Ph. GUILLET, Eric PILON, Zvi BERN, Carl SCHMIDT Nicolas CHANON, Marat GATAULLIN, Serguei GANJOUR, Vasu CHETLURU, Eiko YU

  32. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Backup

  33. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 II. Integrated Lumi/Event Yield forecast for ICHEP (dates) (1) Take 1 and 10pb-1 as ICHEP scenarios

  34. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Photon studies with 2009 Data Data/MC comparisons for 2009 900 GeV data for uncorrected SCVisit our PAS! for corrected SC, photons and for 2360 GeV data  Visit our ANs ! (all done with Jan 29 re-reco of data and MC) Event Selection: Min Bias Trigger: At least 1 hit in one of the BSC (Tech trigger bit 34) Beam crossing: Beam pickup monitor coincidence (Tech trigger bit 0) Tracker HV on (HLT ‘physics declared’ bit) Not beam halo (! Tech trigger bits [36.or.37.or.38.or.39]) At least 1 good PV: n.d.o. f > 4, |z| < 15cm, |d0| < 2cm Anti-”scraping”: >25% high-quality tracks HF: At least one hit E>2GeV in each Supercluster Selection: SC raw Et > 2 GeV Not in barrel-endcap transition: |h| < 1.4442 and 1.566 < |h| < 2.5 ECAL Spike cleaning: (|R19 − 1| < 0.1) CMSSW Version: 3_3_6_patch4 Normalisations to no. of objects in plot In 900 GeV data: 185330 events, 3226 SC (2120 EB, 1106 EE ), same number g

  35. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 ECAL Raw Superclusters h Nsc/event NbasicCluster/SC f Raw E Barrel Raw E Endcap Raw Et

  36. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 ECAL Supercluster Shapes R9=E3x3/Esc Used to choose Eph (conv/unconv) R19=Emax/E3x3 h width F width both used for SC corrs. H/E Used in PhotonId

  37. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 ECAL Corrected Superclusters Corrected E Barrel Corrected E Endcap Corrected Et Barrel Corrected Et Endcap

  38. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Supercluster Isolations Tracker Isolation: Don’t try this in your own home!  Two bugs found in RecoEgamma/PhotonIdentification/src/PhotonIsolationCalculator.cc Fixed by A. Askew in 3_6_0_Pre3, to be backported to 3_5_X For a full explanation see M. Lebourgeois talk: http://indico.cern.ch/conferenceDisplay.py?confId=87047 For fix procedure by P. Musella see: https://twiki.cern.ch/twiki/bin/view/CMS/900GeVECGsupercl#Track_isolation_bug_fix HCAL Isolation ECAL Isolation

  39. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Photon Object Photon E E5x5 Energy used if g judged unconverted Barrel Endcap Endcap Barrel Has not/Has Pixel Seed SC is not/is e cand. Photon Et Endcap Barrel

  40. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Preshower Plane 1 Plane 2 Run-to-Run Stability Raw E SC: Top Barrel, bottom Endcap R9: Top Barrel, bottom Endcap

  41. S. Gascon-Shotkin IPN Lyon/UCBL, CMS Physics France 1avr10 Remaining problems ‘Embedded’ (non-isolated) and low-Pt (<2 GeV) spikes [T. Tabarelli de Fatis/presented by T. Camporesi yesterday’] Some distribs still show relatively poor agreement: e.g. Nxtal/SC esp. in Endcap,under investigation (H. Brun presentation ECAL DPG) E > 3 GeV After time cut After time cut and pulse shape cut kOutOfTime E1/E9<0.95 E1/E9>0.95 E1/E9<0.95 E1/E9>0.95 kFake (pulse shape) Embedded spikes?

  42. ICHEP Plan • Differential isolated photon cross section in pt and eta, with 1~10/pb of data • Detailed studies were performed with 10 TeV MC and documented in CMS AN 2010/026 • Common flat ntuples of 7 TeV 33x Pythia γ+jets and 31x QCD dijet MC have been produced. Purity and efficiency studies are on-going. • Task list for ICHEP and first publication (Thanks to Vasu!) https://twiki.cern.ch/twiki/bin/view/CMS/InclusivePhoton7TeVPaperICHEPPlans • Assign senior persons to monitor and supervise the progress of each task • Integration with the ECAL DPG, EGamma and Tracking POG, PVT, and Higgs/Exotics/SUSY photon groups

  43. A Glance of Task List • https://twiki.cern.ch/twiki/bin/view/CMS/InclusivePhoton7TeVPaperICHEPPlans

  44. Major Tasks More details in later slides • Common Tools • Data Flow: collaboration with EGamma, Higgs/Exotics/SUSY photon groups • Data Quality: collaboration with PVT and ECAL/EGamma • Efficiencies Studies • Photon Purity: collaboration with EGamma • Photon Energy Scale: collaboration with ECAL/EGamma • Systematic Uncertainty • Comparison with Theory • Paper

  45. Common Tools • Common Tree Producer: MultiPhotonAnalyzer (Serguei Ganjour, Ted Kolberg, Mike Anderson, Laurent Millischer, Vasu Chetluru, Vladimir Litvine, Yen-Jie Lee, Pasquale Musella, Abe de Benedetti) • Purity Tool: create templates using output of MPA and extract purity by 2-bin and fitting methods, provide systematic uncertainties (Vasu Chetluru, Vanessa Gaultney, Abe de Benedetti, Pasquale Musella) • Data-driven Efficiency: ZPhotonAnalyzer (Abe de Benedetti) • Run-dependence Studies: monitor variables after event selection and object cleaning (Vasu Chetluru and NN) • MC Efficiency: extract photon efficiency from MC, allow comparison between different generators (Syue-Wei Li, Sudha Ahuja) Close to completeness Just started

  46. An Example Output from Purity Tool • Create templates from functions of any MPA variables • Templates are binned in pt and eta • Report purity by fitting templates • Report purity from 2-bin technique as well M. Anderson

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