W+jets and Rjets (W+jets/Z+jets) : Status Report

1. W+jets and Rjets (W+jets/Z+jets) : Status Report Evelin Meoni On behalf of the Rjets group: G. Arabidze, C. Chavez Barajas, H. Beauchemin, M. Bona, G. Brandt, B. Brau, N. Calace, S. Chouridou, M. Dunford, G. Fletcher, T. Hayashi, J. Huston, R. King, A. Meade, E. Meoni,N. Meric, M. Mondragon, J. Nielsen, J.B. Sauvan, C. Sawyer, A. Tricoli Ed Board Meeting of 3rd May 2013

2. Outline • Brief Reminder of the Analysis Strategy • The status of the Analysis : • - Main updates since the last EdBoard meeting or W/Z presentation • - Ongoing activities • - To Do List • The status of the documentation • In red in the following slides, updates implemented or planned and • questions for EdBoard and convenors

3. Measurement • SET OF VARIABLES ORIGINALLY PLANNED • Njets : inclusive , exclusive and the ratio (njet/(njet-1) ) • Njets for pt_lead > 150 GeV: njet/(njet-1) ( Test scaling differences between W and Z) • Jets: pT and y of 1st , 2nd ,3rd and 4th jet for Njets>=1,2,3,4 (Rjets) also 5th ,6th, 7th jet (W+jets) • Dijets variables: m12,DR12, Df12, Dy12 • Complex : HT and ST for Njets>=1,2,3,4 and for Njets==1,2,3,4 (Rjets) 5,6,7 (W+jets) • Distributions in VBF phase space (mjj>350 GeV, |Dh|>3): pT and y of the 3rd jet • Comparison with LO MCs (Alpgen and Sherpa) and with NLO calculations (BlackHat+Sherpa) • WHAT WE HAVEN’T LOOKED AT YET: • - High jets multiplicity distributions for W+jets paper for Njets>= 5,6,7 (W+jets) • To be done soon (need to update the analysis framework, not in place currently, quite trivial • if ttbar and QCD data-driven work) • Test of the Scaling in high pT regime (W, and differences between W and Z) andVBF • distributions : in place in the framework, but we didn’t look at the results yet. Eventually skip • these variables for time constraints issues (and in Rjets skip also scaling with nominal sel •  Do you (EdBoard and convernors) agree? • -Eventually skip 4 jets distribution in the Rjets paper if uncertainty larger that Z+jets alone

4. Strategy (1/2) • Measurement at detector level : • - Data (2011 stat) and MC (mc11c, pileup reweighting applied, corrected for lepton momentum/energy scale and lep eff SF) • - Signal measured as Data – BKGs: • Hadron level: • Correct for detector effect (trigger and reconstruction eff. and resolution) with Bayesian Unfolding (RooUnfold) in the same phase space of the detector level measurement with Alpgen (dressed leptons) • Comparisons of unfolded data with LO MCs+PS (Alpgen and Sherpa) and with NLO calculation (BlackHat+Sherpa) corrected • Parton level: • NLO calculation corrected by NP effects (fragmentation and UE) and QED effects (born leveldressed)

5. Strategy (2/2) Muons (dressed level) Z: pT(m)>25 GeV|h|<2.4, 66 < mZ < 116 GeV W: pT(m)>25 GeV|h|<2.4, pT(v)>25 GeV, MT > 40 GeV Jet : pT> 30 GeV |y|<4.4 Electrons (dressed level) Z: pT(e)>25 GeV|h|<2.47 (crack excl), 66 < mZ < 116 GeV W: pT(e)>25 GeV|h|<2.47 (crack excl), pT(v)>25 GeV, MT > 40 GeV Jet : pT> 30 GeV |y|<4.4 Combination (dressed level) Z: pT(l)>25 GeV|h|<2.5, 66 < mZ < 116 GeV W: pT(l)>25 GeV|h|<2.5, pT(n)>25 GeV, MT > 40 GeV We’ll publish just the combination Combination Code and References Chi2 method : measurement of Ratio(e) and Ratio (m) first Combination of the 2 Ratios Measurement done first for electron and muon in as similar as experimentally possible phase space: Combination in the common generic phase space : Correction of unfolded electron and muon results for space-phase done with Alpgen About Combination:

6. Event selection Rjets analysis tool on SVN : PhysicsAnalysis/StandardModelPhys/WZJets/Wzratio Based on common W/Z baseline selection: https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/WZElectroweakCommonTopics2011 Preselection: -trigger - primary vertex (at least one good vertex with >=3 track ) -MET cleaning and LAr Hole Veto Lepton selection: Z selection: 2 OS leptons, 66 GeV< mll<116 GeV W selection: MET > 25 GeV, mT(W) > 40 GeV Jets selection: MuonTrigger: mu18_MG (D-I), mu18_MG_medium (J,M) Electron Trigger e20_medium(D-I), e22_medium (K), e22vh_medium1 (L-M) Electrons: Tight ++ Author 1or 3, Quality flag (OQ&1446 !=0) pT>25 GeV|n|<2.47 (excluding 1.37-1.52) Muons: STACO Combined with cleaning cuts (MCP recommendations), pT>25 GeV |n|<2.4 Electrons: 2 OS electrons Muons: 2 OS muons, at least the 1st with d0sign (<3), z0(<10mm), isolation requ. (ptcone20/pt < 0.1) Muons: 1 muon with d0sign,z0, isolation requ. MET: MET_RefFinal, JES and lepton scale prop with MissingETUtility Electrons: 1 tight++ electron Antikt4TopoEM at EM*JES scale pT > 30 GeV, |y| < 4.4 |JVF| > 0.75 ( for jets with |η| < 2.4) ΔR(jet-lepton) > 0.5 • News: Z selection updated to perform a better measurement in term of Ratio • (symmetry between W and Z helps in cancellation of systematics) • - pT(muon/electron) =20 GeV 25 GeV • Same trigger for electron channel in W and Z (already the same in muonch) • Same electron ID for W and Z : 2 OS medium  2 OS tight++ (already the same in muonch)

7. Experimental Systematics JES, JER, MET, Muon, Electron: For each experimental source varied signal and bkg estimated with MC BKGS Varied each bkgs by its uncertainty. MC BKGs uncertainties: 5% Wmn Zmn, Ztt, Wtn; 3-4% single top; 5-7% diboson; 10% ttbar CURRENT STATUS of Systematics Treatment: Needed an update of electron systematics (following latest EGamma group recommendations) CURRENT STATUS of Data-driven BKGs in the Analysis Framework: QCD data-driven estimation and uncertainty in place in detector level and unfolded results : - electron ch: latest results in -muon ch: work/tests on-going, but not an updated estimation available yet used data-driven estimation and sys of early January ttbar data-driven not yet: tests on-going both at detector level and unfolding, but still results produced with MC ttbar (needed all the pieces before replace MC)

8. Detector level plots: an example Example taken by the supporting note Leading jet pT in the electron Channel In the main body of the supporting note just : Njets, pT and rapidity of the leading jet (all the rest in the appendix)

9. On-going tests on data-driven ttbar W- muon channel ttbar (Data-Driven) ttbar (MC)

10. Unfolding(1/2) • Unfolded W and Z in each channel (e,m) separately  Performed R(m) and R(e) Comb • Unfolding technique: Bayesian iterative unfolding with RooUnfold: • - selected events that pass both reco and truth selection • built resp. matrix and fake correction (to account for reco jets in events not passing truth sele) • fake correction applied as a bin-by-bin external correction before unfolding • Unfolding MC: AlpGen • Closure: - Used Sherpa to emulate the data: reco Sherpa events unfolded with Alpgen • - Compared Sherpa unfolded with the truth Sherpa  Closure close to 1 • Unfolding Systematics: • Method: Bayesian vs. Bin-by-bin ; • Modeling: Unfolding with Alpgen vs. Sherpa • Statistical Uncertainty:Toy MCs to fluctuate the matrix (RooUnfold implementation) PLANNED UPDATES: Statistical Uncertainty: write our implementation properly varying all unfolding inputs (matrix truth and reco distributions , fake) Modeling : Difference between Alpgen and Sherpa seems somehow conservative , this could have an impact in the Ratio measurements (one of the main uncertainties) Planned a rebining of a set of distributions (help against statistical fluctuations) Try to look at Alpgen samples with different parameters (samples available by SUSY group), it could take time Do you (EdBoard and convernors) agree?

11. Unfolding (2/2) Convergence criterium for N_iterations (FINALISED) -Best number of iteration is the one for which the total unfolding systematics is minimal -Studied convergence value (unfolding uncertainty mediated on the all the bins of the measurement) vs number of iteration Minimum around 1-3 iteration, no large difference of the minimum in this range: Chosen 2 iterations for all variables Z W RATIO

12. Systematics on unfolded results W muons For each source varied signal (matrix and fake correction) and bkg estimated with MC (for unfolding unc source moved signal only, for bkg unc source moved bkg only) electrons Z • Something to be fixed in electron channel • When full chain applied (loop over all the • systematics, varying all components) • “funny results” obtained. • A lot of investigations on-going: • It is not a problem of the unfolding proc or of systematics implementation • Maybe (tests on-going) histograms overwritten in the loop  not proper set • of shifted histograms used • Current results obtained with a “trick” (no • fake correction applied) muons electrons RATIO muons electrons

13. On-going tests on data-driven ttbar ttbar (Data-Driven) ttbar (MC) Preliminary W- muon channel • Not fair comparison, but it gives an idea: • MC case: just 10% uncertainty in ttbar normalization taken (kept ttbar fixed to the nominal • value when JES/JER and letpton uncertainties varied) • Data-driven case: 2 sources of uncertainties for ttbar (JES, light/heavy flavor jets efficiency), • ttbar JES uncertainty components correlated with the other JES terms. • Jets efficiency uncertainty evaluated as residual ttbar uncertainty in bkg term • Strong reduction of the uncertainty at large multiplicity , but exercise to be completed (full list • of syst, check impact on the Ratio)

14. Predictions • NEWs: • -New Z predictions (with pT(lepton)>25GeV) : basically same grid of the previous one , just • slightly smaller statistics due to the increasing of pT cut • An update on the calculation of the systematics for UE and hadronisation: • before sum in quadrature of UE and hadronisation effects  now compared the 2 sets of samples • after both UE+hadr effect • - Work on the sys finalized also for the Ratio, prediction uncertainty band included in the results NLO pQCD preditions with BlackHat+Sherpa : CT10 PDFs , ren and fact scale at HT/2 (scalar sum pT of all particles/partons in final state) Corrections : Nominal correction derived from Alpgen+Herwig (Auet2-cteq6l1 tune )syst estimated with Alpgen+Pythia (Perugia2011C)(UE and hadronization) and Sherpa (QED corrections)

15. Results: an example News: - Shown Black+Sherpa uncertainty band - Electron plots with all systematics in (even if still needed fixing of the values, no fake applied) - Rebinning already in place in detector level plots, not applied yet at undolding level

17. To do list: summary • QDC data-driven: • already in place in the skeleton of the analysis , but needed finalization of • the work in terms of nominal values and uncertainties, • mainly in the muon channel (work on-going but status not advanced) • ttbar data-driven: • - Tests on going for W channel to include it in the framework of the analysis, but still • not complete (soon missing pieces will come, the implementation will be fast) • - Needed estimation for the Z channel (both electron and muon): • work not started yet • - Unfolding: • - Problems systematics in electron channel need to be solved soon •  main obstacle to proceed with combination and to retrieve final conclusions • - Some work needed for systematics (minor things): • statistical term and modeling one in the unfolding • update of the electron term systematics • - Combination: • - Code set-up with all the inputs available so far • - Needed to be completed with the full list of inputs and tested once the results of • the single channels will be validated (mainly in electron channel)

18. Status of the documentation As agreed just one supporting note for W+jets and Rjets. Currently 315 pages (about 50 pages of text the rest plots and appendices) • Structure defined since a while, a lot of information there and the most updated plots • Still not ready for CDS or SM circulation, but mature enough for EdBoard with some advice • What can you read? (in red what you cannot read yet) • 1.Introduction (even if it will extended in the next and we will add W+jets part) • 2. Data and MC simulation samples • 3.4. Electron Channel and Muon Channel • But don’t look at QDC sessions (both nominal • estimation and syst) and ttbar systematics (in ele ch ttbar missing, details will be added in the next) • 5. Detector Level Systematic Uncertainties • 6. Corrections to particle level • 7. Systematics Uncertainties on Unfolded Results • But don’t pay too much attention at electron plots!Still missing comments on the results

19. Status of the documentation What can you read? 8. Combination of electron and muon channels Don’t read we don’t have results yet.What we will add here: - pulls - final combined plots - unfolded systematics breakdown tables - maybe plots of the acceptance corrections 9. BlackHat+SHERPA Theoretical predictions 10. Results Eventually just look at muon plots, no text there, for some distributions we need to do some cross-check 11 Conclusions A,B,C,D,E,F Appendix Ok, just collections of plots Basically , don’t read QDC part (text and plots), electron unfolded results (not final) , combination (missing) But the full analysis strategy and a lot of plots are there Maybe in the next some minor update in the structure (almost systematics plots of unf results in the appendix, more symmetric description of electron and muon ch)

20. BACKUP

21. Data and MC samples • Normalized to (N)NLO XS: • https://svnweb.cern.ch/trac/atlasgrp/ • browser/Physics/StandardModel/ • Common/Winter2012/mc11c_p833_info.txt • -QCD estimated with data driven-techniques • -top : currently estimated via MC • use Data-Driven estimation in the next 2011 Data: - period D-M - GRL: data11_7TeV.periodAllYear_DetStatus-v36-pro10_CoolRunQuery-00-04-08_WZjets_allchannels.xml - 4.64 fb-1 for each stream (EGamma and Muon) - SMWZ D3PDs tag p833 MC: -mc11c samples

22. Technical remarks: tags Electrons: egammaAnalysisUtils-00-04-25 ElectronEfficiencyCorrection-00-00-13 Muons: TrigMuonEfficiency-00-02-30 MuonMomentumCorrections-00-07-00 MuonEfficiencyCorrections-02-01-11 JETS: JetUncertainties-00-08-05 ApplyJetCalibration-00-03-03 ApplyJetResolutionSmearing-00-01-02 JetResolution-02-00-02 MET: MissingETUtility-01-00-09

23. Converge criteria for unfolding Convergence criterium, 3 method under evaluation: 1) 2011 Z+jets paper approach: 2) (close to) 2010 W+jets paper approach: 3) Best iteration is the one for which the unfolding uncertainty on XS results is minimal Used Sherpa to emulate the data and Alpgen to unfold Stop iterations when difference on 2 consecutive is smaller of the statistical unc I meth Z II meth Z III meth Z

24. On-going tests on ttbar Previous results ttbar (Data-Driven) ttbar (MC) 24

25. On-going tests on ttbar Previous results ttbar (Data-Driven) ttbar (MC) W- muon channel Not fair comparison, but it gives an idea: MC case: just 10% uncertainty in ttbar normalization taken (kept ttbar fix to the nominal value when JES/JER and letpton uncertainties varied) Data-driven case: 3 sources of uncertainties for ttbar (JES: just the main of the JES component, JER, light/heavy flavor jets efficiency) , ttbar JES and JER unc. correlated with the JES and JER Terms. Jets efficiency uncertainty evaluated as residual ttbar uncertainty in bkg term  Reduction of bkg uncertainty component, but exercise to be repeated