1. 1 Report from the LPC JetMET group Robert Harris Marek Zieliński Fermilab Rochester Advisory Council Review of LPC 22 October 2004

2. Robert Harris, Marek Zieliński 2 Outline l The LPC JetMET group è Goals è Members l Calorimeter Issues è Detector aspects  Geometry  map of calorimeter towers è Lego display l Jet studies è Jet algorithms and software è Analyses: à Response à Jet Corrections è Simulation: OSCAR and FAMOS l MET studies: resolution, significance l Plans for Physics TDR, future work l Conclusions and Outlook HB HE HF HCAL

3. Robert Harris, Marek Zieliński 3 LPC JetMET Information l Conveners è Robert Harris (CMS & CDF) rharris@fnal.gov rharris@fnal.gov  Marek Zieliński (CMS & D Ø ) marek@fnal.gov marek@fnal.gov l Meetings è Bi-weekly è Agenda available from http://agenda.cern.ch l Web page è http://www.uscms.org/scpages/ge neral/users/lpc_jetmet/lpc_jm.html http://www.uscms.org/scpages/ge neral/users/lpc_jetmet/lpc_jm.html è Current information on data, software and getting started in JetMET l Mailing List è lpc_jetmet@fnal.gov lpc_jetmet@fnal.gov

4. Robert Harris, Marek Zieliński 4 LPC JetMET Members l Heads è Rob Harris (FNAL) and Marek Zieliński (Rochester) l At FNAL è Daniel Elvira (FNAL), Marc Paterno (FNAL) è Shuichi Kunori (MD), Jordan Damgov (FNAL), Taylan Yetkin (FNAL), Kenan Sogut (FNAL), Selda Essen (FNAL), Stefan Piperov (FNAL) l Away è Salavat Abdullin (FNAL), Lalith Perera (Rutgers), Maria Spiropulu (CERN) l Joining è Alexi Mestvirshvili (Iowa), Dan Karmgard (Notre Dame), Taka Yasuda (FNAL), Nobu Oshima (FNAL), Weimin Wu (FNAL)

5. Robert Harris, Marek Zieliński 5 Relation to Broader CMS l Working with the PRS JetMET group è Our work on jet studies began within PRS JetMET è Contributing to PRS meetings è Frequent exchanges on current issues, coordination è Chris Tully has attended our meetings, provides guidance l Collaborating with Fermilab HCAL group è Participating in mutual meetings è HCAL people becoming active in LPC JetMET è Opportunity for a leading calorimetry-based software effort at Fermilab, in addition to the well-established hardware role l Interacting with other LPC groups

6. Robert Harris, Marek Zieliński 6 Ongoing LPC JetMET Efforts l Learning about detectors, JetMET software, simulation l Calorimeter studies, evaluation/feedback for lego display l Jet studies  Jet energy response and corrections as a function of P T and  l MET studies: è Resolutions and significance l Simulation è Response to jets and single pions in FAMOS (fast simulation, ~1 s/ev), compared to OSCAR (full G4 simulation, ~10 min/ev) è Test/tune the simulation to make it adequate for jet use à In coordination with the LPC and CMS Simulation groups l Aiming for growing and increasingly important role in support and development of jet and missing-E T software

7. Robert Harris, Marek Zieliński 7 Ongoing Efforts II - HCAL/Test Beam l TB2002-TB2004 analysis -- data taking finished this Monday è Extraction of key parameters for detector simulation and event reconstruction à Pulse shape, pulse timing, electronics noise, ADC-to-GeV, etc. è Checking detector effects à Gaps, uniformity, abnormally large signal, etc. è Development of algorithms for calibration, monitoring and data validation è Test of GEANT4 physics  e/ , resolution, longitudinal & transverse shower profile  3--300 GeV beams, with particle-ID (p, K, , e) below 9 GeV l Physics benchmark studies ramping up – Goals: è Identify issues in event reconstruction and triggering à Then develop/improve algorithms è Provide experience of physics analysis to young members l Software development and maintenance è JetMET RootMaker (J. Damgov) è HF Shower library (T. Yetkin) è HCAL database

8. Robert Harris, Marek Zieliński 8 Aspects of CMS Calorimetry l Learning calorimetry issues that impact JetMET: è Several detectors contribute: ECAL, HB, HO, HE, HF à Complexity of geometry: overlaps, gaps, transition regions è Different detection technologies in use: à PbWO 4 crystals (ECAL), scintillator (HB, HO, HE), quartz fibers (HF) è Essential feature: Non-compensation à e/h ~1.6 ECAL, ~1.4 HCAL à Non-linear response  Significant tracker material before the calorimeters (0.2--0.4 0 ) è Significant noise levels (hundreds of MeV/channel) è Event pileup (~3 events/crossing even for low luminosity) è Inside high magnetic field (affects light yield, sweeps low P T particles…) l Challenge for algorithms to maximize performance

9. Robert Harris, Marek Zieliński 9 Calorimeter: Geometry Understanding of basic geometry  crucial for code development and interpretation of simulations è Verifying geometry in software vs. actual construction  -  map of HCAL towers è Constructed a map from information found in HCAL TDR, updates ongoing à Connection to HCAL group is an invaluable resource

10. Robert Harris, Marek Zieliński 10 Calorimeter: a Lego-plot Display l Communicating with IGUANA experts at CERN è The functionality of the lego display was requested by the LPC JetMET à We are involved in testing and provide feedback to developers è Initial “toy” version displayed simulation hits only in the Barrel (below) è A more realistic display of EcalPlusHcalTowers for all regions is being developed

11. Robert Harris, Marek Zieliński 11 CMS Jet Algorithms l CMS jet algorithms can cluster any 4-vectors: partons, particles, towers etc. è Cone algorithms (with different cone sizes and recombination schemes) à SimpleConeAlgorithm ð Throws a cone around a seed direction (i.e. max P T object) à IterativeConeAlgorithm ð Iterates cone direction until stable à MidPointConeAlgorithm – CMS version: no splitting/merging (same as above) ð Uses midpoints between found jets as additional seeds à MidPointConeAlgorithm – Tevatron RunII version, with splitting/merging è KT algorithms: iterative clustering based on relative P T between objects à KtJetAlgorithm ð Iterates until all objects have been included in jets (inclusive mode) à KtJetAlgorithmDcut ð Uses the stopping parameter D cut à KtJetAlgorithmNjet ð Forces the final state to decompose into N jets l A more comprehensive “vertical” slice of the jet reconstruction code, from DST to root-tuples, is included in the backups

12. Robert Harris, Marek Zieliński 12 Examples of Building and Running l We provided basic examples to help new users to start contributing (available from webpage)  Tool to test jet reconstruction by printing out jet  and  è Code to create a simple root tree with selected jet variables è Examples include: à Scripts to compile and link the programs on CMS UAF à Generic script to run the programs on CMS UAF à Script that runs the jobs on specific DC04 dataset (QCD) à Typical output logfiles à A small output root-tree l Our webpage includes additional resources and links to full- blown JetMET tutorials, UAF information, software tools and Monte Carlo datasets

13. Robert Harris, Marek Zieliński 13 Studies of Jet Response and Corrections l Work has been requested by PRS JetMET group è Correction software completed in ORCA and available to CMS l P T of reconstructed jets is not same as of the particles in the jet: è Calorimeter has non-linear response to charged pions and jets vs. P T  Calorimeter has significant response variations vs.  l Goal: provide software to correct the reconstructed jet P T back to the particles in the jet è For now, considering jet algorithms that use only calorimeter information è Current study is based on the knowledge of “Monte Carlo truth”  Need to develop data-based jet calibration methods, using response to tracks and P T -balancing in dijet,  -jet and Z-jet systems We determined, as a function of P T and  è Response = Reconstructed Jet P T / Generated Jet P T è Correction = 1 / Response

14. Robert Harris, Marek Zieliński 14 Jet Corrections and Closure Tests l Response studied using QCD dijet samples, P T Gen = 15 -- 4000 GeV The measured average response was parameterized with functional forms vs. jet P T and  è For Iterative Cone, R=0.5, tower E > 0.5 GeV, lum = 2 x 10 33 cm -2 s -1 l Applying parameterized corrections: è Is correcting back to particle-jets before pileup è Makes original response functions flat  Correction good to ~1% for Rec Jet P T > 30 GeV, |  | < 1  Correction good to ~2% vs.  è Another test: seems to work OK for the reconstructed dijet mass spectrum l Corrections currently implemented in the JetMetAnalysis package of ORCA

15. Robert Harris, Marek Zieliński 15 Jet Response vs.  (Relative to |  | < 1) Before Corrections After Corrections 25<P T <3030<P T <4040<P T <60 60<P T <1200120<P T <250250<P T <500 500<P T <10001000<P T <2000 2000<P T <4000

16. Robert Harris, Marek Zieliński 16 Discussion of Jet Response vs. P T &  l Response vs. P T è Response rises with increasing P T for P T > 40 GeV à As expected from non-linear response of calorimeters to pions è Response rises with decreasing P T for P T < 40 GeV à Thought to be a result of contributions from noise and of tails in the resolution of response Response vs.   In Barrel: decrease in response with increasing  at low P T  Noise contribution to jet energies is ~several GeV; its influence on P T diminishes with increasing   In Endcap: increase in response with increasing  à Interpreted as due to improved linearity with increasing E, and to migration of soft spiraling particles into the Endcap è In Forward: higher level of response than in Barrel or Endcap à Thought to be partially due to HF calibration in MC 25<P T <30

17. Robert Harris, Marek Zieliński 17 Studies for FAMOS l PRS JetMET requested involvement of the LPC JetMET group l CMS needs a reasonably accurate and fast simulation for jets è FAMOS is three orders of magnitude faster than OSCAR at high P T l We seek to understand the current status of FAMOS for jets è How does it work? è Does it accurately reproduce mean jet response? è Does it accurately reproduce jet resolution? l First step – done è Compare FAMOS and OSCAR for jet response and resolution  Compare the basic parameters in FAMOS to those for testbeam l Next steps: è Improve the FAMOS parameters, tune to OSCAR è Port CMSJET/GFLASH implementation of fast showering è Deadline for tuning of HCAL in FAMOS is December 2004 for Physics TDR

18. Robert Harris, Marek Zieliński 18 Mean Jet Response vs. P T and  l Features of FAMOS / OSCAR response comparisons: è Both FAMOS and OSCAR responses increase with P T for P T > 30 GeV à As expected from improving linearity at higher E  FAMOS response agrees well with OSCAR for |  | < 1  FAMOS response is higher than OSCAR for |  | > 1, needs tuning à FAMOS has up to ~20% higher response at low P T l Distributions of response also in reasonable agreement (see backups) |  |<11<|  |<22<|  |<3

19. Robert Harris, Marek Zieliński 19 MET Reconstruction l Several levels of MET reconstruction è From calorimeter towers è From towers with track corrections (E-flow type)  Using reconstructed objects (jets, e,  …) à This involves many possible variations for different: ð object definitions (eg. Jet algorithm)  type/level of corrections (  s, tracks, pileup, jet calibration…) l Important issues è Propagating corrections for pions, jets and muons è Corrections for low-P T tracks (“loopers”) è Understanding of unclustered energy, calibration è Channel thresholds, noise, pileup l Hence, many studies needed - help welcome l For now, we focus at the calorimeter-level definition (using EcalPlusHcalTowers)

20. Robert Harris, Marek Zieliński 20 MET Resolution Studies l Use the same QCD dijet samples as for jet studies   E T range 200 – 8000 GeV MET and  E T calculated from calorimeter towers l Studies of sensitivity to energy cutoffs, parameterization of resolution, work towards E-flow expected in near future MET resolution vs.  E T

21. Robert Harris, Marek Zieliński 21 LPC JetMET Plans and Physics TDR l Development and support of the jet and missing-E T software is our major goal è Need the commitment of software experts in addition to volunteer physicist effort è The LPC is pursuing the appropriate resources for this task l We have already started contributing to several areas that will be part of the Physics TDR, as identified by the PRS JetMET leadership (see backups) è Understanding jet response and corrections è Understanding MET resolutions è FAMOS for physics studies è Physics channels: dijet mass for QCD and Z’ dijet resonance search l We will expand our contributions as the necessary resources become available è Calibration and trigger è Physics channels that focus on understanding HCAL and JetMET issues (some students already assigned) à QCD dijet production and dijet resonance searches à SUSY in the jets + MET channel à qqH à Top, ttH l Coming soon: a 1-day JetMET/HCAL/P-TDR workshop on November 12, 2004 (coordinated by the PRS JetMET group)

22. Robert Harris, Marek Zieliński 22 Conclusions and Outlook l The LPC JetMET effort is gearing-up strongly è Our expertise in detector issues, software, simulation is rapidly increasing è New people are joining and starting to contribute è Interactions with HCAL and PRS JetMET efforts have opened many avenues for involvement l Physics TDR is an excellent opportunity to establish ourselves within CMS and to hone the skills l Have to be ready for Day One l We need your support, postdocs, students!

23. Robert Harris, Marek Zieliński 23 Backup Slides

24. Robert Harris, Marek Zieliński 24 General Goals l Form a center at Fermilab for USCMS expertise in JetMET è Data à Where it is, how to get it, how to analyze it è Software à Understanding and contributing to the Jet, MET and calorimeter code à All levels, from the reconstruction to the root tree and beyond è Analysis Tools and Techniques à Simulations, Event Displays, Jet Corrections, etc. l Work in coordination and cooperation with PRS JetMET group l Help prepare USCMS for analysis of first CMS data è Understand LHC phenomena involving jets and/or MET è Be ready for possible discovery of new physics phenomena involving jets and/or MET

25. Robert Harris, Marek Zieliński 25 Tevatron Experience with Jets l Midpoint algorithm is the primary variant; KT algorithm also used l Adding 4-vectors (E-scheme) preferred to E T -weighting (E T -scheme) è But: is it optimal for “bump” searches? l Splitting and merging essential for physics l Low-P T jets affected by detector noise è Various protections developed l Algorithms have to be robust against underlying event, multiple interactions è KT algorithm appears particularly sensitive l Resolution improvements using tracks being developed Due to hot cells

26. Robert Harris, Marek Zieliński 26 CMS Jet Software: High Level Map Vertical slice of the jet reconstruction code: l RecJetRootTree: Produces root tree with jet info l RecJet: Persistent jet object RecJet l PersistentJetFinder: Calls the jet algorithm to make the jets PersistentJetFinder l IterativeConeAlgorithm: Example jet algorithm which clusters the constituents (the towers, or tracks, etc.) IterativeConeAlgorithm l VJetableObject: Class that holds the jet constituents VJetableObject l VJetFinderInputGenerator: Virtual class to fill list of generic jet constituents (vector of VJetableObjects) VJetFinderInputGenerator l JetFinderEcalPlusHcalTowerInput: Class to fill list of towers in calorimeter (vector of VJetableObjects with EcalPlusHcalTowers) JetFinderEcalPlusHcalTowerInput l EcalPlusHcalTower: Class for building ECAL + HCAL towers EcalPlusHcalTower

27. Robert Harris, Marek Zieliński 27 Examples of Building and Running TestRecJet.cpp: Program to test use of RecJet by printing out jet  and  l BuildTestRecJet.csh : Script to compile and link the program on CMS UAF BuildTestRecJet.csh l RunTestRecJet.csh : Generic script to run the program on CMS UAF RunTestRecJet.csh l JobTestRecJet.csh : Script that runs job on specific DC04 dataset (QCD) JobTestRecJet.csh l jm03b_qcd_230_300.txt : Output log file for QCD dijets with 230 < P T < 300 GeV jm03b_qcd_230_300.txt RecJetRootTree.cpp: New code to create root tree with jet information l BuildRecJetRootTree.csh : Script to compile and link the program on CMS UAF BuildRecJetRootTree.csh l RunRecJetRootTree.csh : Generic script to run the program on CMS UAF RunRecJetRootTree.csh l JobTestRecJet.csh : Script that runs job on specific DC04 dataset (QCD) JobTestRecJet.csh l RootTreeJob_jm03b_qcd_230_300.txt : Output log file RootTreeJob_jm03b_qcd_230_300.txt l RecJet.root : Output root tree with 10 events RecJet.root

28. Robert Harris, Marek Zieliński 28 Jet Response vs. P T l Response studied using QCD dijet samples, P T Gen = 15 -- 4000 GeV l Root trees that just contain generated and reconstructed jets written on CMS UAF at Fermilab è Gen and Rec jets matched if R<0.4 l Response shows Gaussian behavior at high P T, but deteriorates at low P T 240 < P T < 48018 < P T < 24

29. Robert Harris, Marek Zieliński 29 Jet Response vs.  (Relative to |  |<1) 25<P T <30 30<P T <4040<P T <60 60<P T <1200120<P T <250250<P T <500 500<P T <10001000<P T <20002000<P T <4000

30. Robert Harris, Marek Zieliński 30 Distributions of Jet Response

31. Robert Harris, Marek Zieliński 31 Using (0,0) Tevatron Experience with MET l Great tool for finding detector problems! è Removal of hot channels crucial è Distributions of METx, METy used to monitor running conditions, declare bad calorimeter periods l Important issues è Propagating corrections for jets and muons è Understanding of unclustered energy, calibration  Low channel thresholds, large  coverage l Sensitive to alignment and vertexing Beam spot 0 Using correct X-Y interaction position  

32. Robert Harris, Marek Zieliński 32 PRS JetMET Plans and Physics TDR l HLT and physics object reconstruction è Development and maintenance of Jet ORCA code è Development and maintenance of MET ORCA code è HLT event selection è Validation of performance l FAMOS è Verification of physics objects è Verification of OSCAR/ORCA agreement è Event monitoring è Analysis examples è Interface to jet reconstruction è Interface to MET reconstruction è Single-particle hadronic shower response l Simulation è Geometry: HB HE HO HF è Geant-4 shower è Geant-4 Cerenkov è Pulse shape and timing è HO trigger l HCAL Calibration è Radioactive source è Library of responses è Gamma + jet è W from top è Jet corrections è MET corrections l Data Base è Construction è Equipment è Configuration è Conditions è Monte Carlo l Detector Controls è Parameter downloading è High Voltage è Low Voltage è Laser è LED è Source è Jet and MET response tuning l Local DAQ è XDAQ è Interface with DCS l Data monitoring è Online monitor è Offline monitor è Radiation damage l Test beam è RECO code maintenance l Physics TDR analysis è qqH à Study of trigger turn-on curves à Dilepton, MET and forward tagging jet preselection à Lepton + MET + high Pt W hadronic decay + tag jets preselection à Jet resolution and energy scale for forward tagging-jets à MET resolution à Top and multijet backgrounds à Top and W + n jet backgrounds à Diboson + n jet backgrounds à Primary vertex assignment for central jet veto à b-ID veto à Mass analysis à algorithms of high Pt W->qq mass reconstruction è Z-prime to jets à Study of trigger turn-on curves à Jet Response Linearity and Calibration à QCD background à Dijet mass resolution and background shape determination à Centrality and spin analysis à Multiple Resonances and large width analysis è SUSY à Study of SUSY working points for general search à Study of trigger turn-on curves à MET reconstruction and calibration à Jets+Missing energy preselection à W/Z+Njet, ttbar and QCD backgrounds à Lepton triggering à Mass difference analysis è QCD è Top