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The ALICE EMCal-PPR strategy / progress

The ALICE EMCal-PPR strategy / progress. Rene Bellwied Wayne State University EMCal Software / PPR Meeting, Frascati May 19-21, 2009. Purpose of the document.

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The ALICE EMCal-PPR strategy / progress

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  1. The ALICE EMCal-PPRstrategy / progress Rene Bellwied Wayne State University EMCal Software / PPR Meeting, Frascati May 19-21, 2009

  2. Purpose of the document • Originally requested by the Department of Energy (to be completed by June 2009) in order to formulate the physics scope of the EMCal for ALICE. • Based on discussions with ALICE the EMCal PPR will become an official addendum to the existing ALICE PPR. • We aim for official (J.Phys.G ?) publication along the lines of the original ALICE-PPR • Working on an extension until October 2009

  3. Organization • Report coordinator: Rene Bellwied (Wayne State) • Five prioritized sub groups with group coordinators 1.) jet reconstruction (Joern Putschke) 2.) EMCal triggering (Mateusz Ploskon) 3.) photons and gamma jets (Gustavo Balbastre Conesa) 4.) electron and heavy quark tagging (Jennifer Klay) 5.) particle identified jet measurements (Rene Bellwied) • Bi-weekly EVO meetings, face-to-face meetings planned around ALICE weeks, ALICE-US collaboration meetings, EMCal meetings. Next meeting during ALICE week, late June) • web-page: http://alice.physics.wayne.edu • Report to PWG-3, PWG-4 and ALICE Physics Board regularly (either the group coordinators or the report coordinator)

  4. Define calorimeter driven physics goals • Measure parameters that determine energy loss mechanism (e.g. transport coefficient, color charge density, as)), energy flow (r/R), jet cross section (jet RAA) • Jet reconstruction of hadron jets and gamma jets • Determine level of medium response through correlation analysis (jet broadening, jet shape, particle correlations). Specify medium parameters (viscosity, speed of sound etc.) • Jet correlation measurements • Determine relative strength of recombination and modified fragmentation as a function of transverse momentum. Explore hadronization, jet flavor conversion. • Identified particle measurements in jets • Determine light / heavy quark energy loss and hadronization differences. • Jet reconstruction of electron jets • Determine medium modification in jets related to chiral symmetry • Identified resonance measurements in jets

  5. General strategy • For jet reconstruction, triggering, photon, and electron physics improve on the existing simulations as shown in the CD-2 final physics report and recent EMCal TDR. • For particle identified jet measurements and jet correlations develop a performance report and interface with multiple other detector components in ALICE (TPC,TRD, ITS, PHOS)

  6. EMCal PPR – proposed Table of Content 1.) EMCal Physics - theoretical overview 2.) EMCal Detector Layout 3.) Simulation Framework and MC Generators 4.) EMCal Detector Performance • Energy resolution • Jet energy resolution • Trigger performance • Jet trigger • Photon trigger • Electron trigger • Gamma/pi0 identification • Hadron/electron discrimination 5.) EMCal Physics Performance

  7. EMCal PPR – Physics Performance Breakdown A.) Jet reconstruction • Comparison of jet algorithms • Jet reconstruction corrections • hadronic energy corrections • neutral energy correction • final jet energy resolution • effects of v2 and radial flow • Jet reconstruction in pp • jet energy and yield • jet axis and width • Jet reconstruction in AA • jet energy and yield • jet axis and width • Fragmentation functions in pp • Fragmentation functions in AA • Constraints on energy loss models • jet broadening measurements • sub-jet distribution • modified fragmentation functions • Constraints on medium response models • jet correlation measurements B.) Photon and gamma-jet reconstruction • Photon reconstruction • Isolation cuts • Gamma-jet reconstruction • Comparison to PHOS physics performance • Photon-tagged jet analysis • fragmentation functions • constraints on models • C.) Electron and heavy flavor jet reconstruction • Electron reconstruction • Electron-jet reconstruction • Heavy quark energy loss • Heavy quark fragmentation functions • D.) Identified particle studies in jets • High momentum PID in ALICE • Identified jet yields and ratios • Identified fragmentation functions in pp • Identified fragmentation functions in AA • Constraints on fundamental QCD processes • Constraints on energy loss and • medium response models • Resonances in jets

  8. Specific Strategies since TDR • Use more realistic event generators, in particular for in-medium modification (tool 1) • Use better jet algorithms in particular fast-jet package (tool 2) • Use data driven detector performance benchmarks (based on test beam and calibration) • Use data driven analysis tools (based on STAR)

  9. Tool 1: ‘Realistic Event-generators’ Monte Carlo Implementations: PYQUEN (Lokhtin, Snigriev): PYTHIA afterburner reduces energy of final state partons and adds radiated gluons according to BDMPS expectations. PQM (Dainese, Loizides, Paic): MC implementation of BDMPS quenching weights HIJING (Gyulassy, Wang): jet and mini-jet production with induced splitting JEWEL (Zapp, Ingelman, Rathsman, Stachel, Wiedemann): parton shower with microscopic description of interactions with medium q-PYTHIA (Armesto, Cunquiero, Salgado, Xiang): includes BDMPS-like radiation in modified splitting function YaJeM (Renk): medium increases virtuality of partons during evolution

  10. Tool 2:Jet Reconstruction Algorithms(FastJet Package) seed • Seed Cone: • ‘seed’ (E>Ethreshold) • iterative approach • Seedless Cone (SIS cone): • all the particles used as seeds • Splitting/Merging applied fragmentation tracks or towers Cone Algorithms outgoing parton Rcone seed R=√(Δφ2+Δη2) [Cacciari, Soyez, arXiv:0704.0292] • Seedless, not bound to a circular structure • kT: starts from merging low pT particles close in the phase-space • Anti-kT: starts from merging high pT particles close in the phase-space Recombination Algorithms [Cacciari, Salam, Soyez, arXiv:0802.1189]

  11. Status Detector Performance Jet reconstruction (Joern Putschke) Trigger (Mateusz Ploskon) Photons (Gustavo Balbastre Conesa) Electrons (Jennifer Klay) Identified Particles /Resonances (Francesco Blanco, Renaud Vernet, Christina Markert, RB)

  12. Jet energy resolution from STAR data in pp collisions (H.Caines QM09)

  13. Jet energy resolution from STAR data in pp collisions (H.Caines QM09)

  14. Jet reconstruction in TDR • Attempt to extend the reliability of jet finding algorithm to jet energies below 100 GeV. Important for single jets, crucial for jet correlations. • Optimize jet finding algorithm through comparison (FastJet) • Optimize quenching simulations, estimate effects elliptic and radial flow, hadron corrections, electron conversions, jet-energy correction

  15. Example: Sensitivity to transport coefficientMost asked question:Can you, based on your simulation, tell us how sensitive you are to qhat within the ASW approach ?

  16. Fake jet subtraction Different approaches shown at QM by: E. Bruna (STAR): use C&S with off-axis ‘jet’ spectrum M. Ploskon (STAR): part of spectrum unfolding (event mixing) Y.S. Lai (PHENIX): Gaussian filter Additional publications by: Cacciari & Salam (Phys.Lett. B659, 119 (2008)): s / sqrt(<A>) ATLAS HI (arXiv:0810.1209): SjT

  17. I.Vitev et al. (arXiv:0810.2807)Jet shapes

  18. No EMCal, PYTHIA jets in HIJING background (jet data challenge) Related results (ALICE-PPR)

  19. Theory prelim.STAR data Jet cross sections Related STAR result (M.Ploskon, QM09) STAR Preliminary RAA for jet cross section evolves continuously by varying cone size and acceptance cut. Contrast: single result for leading particle Limits: RAA approaches to single hadron suppression with very Rmax and large ωmin

  20. T. Renk (arXiv:0808.1803)medium modified fragmentation function This is a calculation for RHIC energies but Thorsten could certainly provide a comparable simulation for the LHC

  21. pT(trigger)>20 GeV Ptcut=2 GeV pT(recoil)>25 GeV (reduce fake jets to <10%) Ptcut=0.1 GeV Medium modified fragmentation functionRelated STAR result (E. Bruna, QM09) “trigger” jet “recoil” jet No major modification without any pTcut on tracks and towers

  22. Recent studies of jet triggering • Attempt to extend the trigger efficiency for jet energies of 50-100 GeV. Check effect of jet quenching • Optimize LVL-1 algorithm by taking altering patch size/geometry based on new mapping manipulations (elelctronics). • Optimize HLT based on EMCal

  23. Triggered jet yields in one LHC year Jet yield in 20 GeV bin • Another factor 5 is possible by triggering TPC at 500 Hz instead of 100 Hz and using EMCal L1/HLT to cut recorded rate down to 100 Hz

  24. Jet trigger and wrong slope extrapolation can make large difference in particle yield estimates EMCal PPR Original ALICE-PPR Reach out to 12 GeV/c or 30 GeV/c per year ?

  25. Direct photons and gamma-jets • Optimize shower shape algorithms, isolation cuts Shower shape study, PbPb quenched Isolation cut study, PbPb quenched

  26. R. Fries et al. (arXiv:0801.0453):jet-photon conversions Annihilation (q-qbar to  or q-qbar to  g) or Compton (q g to  q)

  27. Latest gamma-jet simulations • The modification of the fragmentation function can be measured for 30 GeV photons in the range of 0.5 < x < 3.2. • HI Background is the main source of error. Need more studies on: bkg area, min pT cut, jet-jet bkg, photon Isolation • Comparison: PYTHIA / HERWIG / NLO pQCD Ratio pp / PbPb

  28. W. Horowitz (arXiv:0710.0595)heavy quark energy loss in the strong and weak coupling limit

  29. Activities Matrix – group 4

  30. Simulation run status • Discussions with Latchezar Betev, Peter Hristov, Federico Carminati • Jennifer Klay, Gustavo Balbastre Conesa, Magali Estienne • HIJING more time consuming than jet runs

  31. Production cycle status (5/16/09)

  32. FastJet / JetAn status Andreas’ latest modifications • Fastjet packages including cgal are now on the grid: • VO_ALICE@boost::v1_38_0 VO_ALICE@cgal::v3.3.1 VO_ALICE@fastjet::v2.4.0 • Test example is in (alien) /alice/cern.ch/user/m/morsch/fastjet/ • Andreas prepared a special JETAN.par

  33. JetAn / FastJet status Magali’s latest modifications • JETAN now uses charged + neutral information. • Jet finder now has options (UA1, FastJet, SISCone), can look for jets including "neutrals". • Hadron correction based on Geant 3 included (no FLUKA). • No electron correction part yet. • Both corrections (hadronic and electron) are applied at the level of the reader of the code. • Background subtraction includes the possibility to work on a limited EMCal acceptance (cut on eta and phi in the eta/phi grid). • Possibility of smaller resolution parameter R is not yet included.

  34. Summary & Outlook Work plans and strategies for an effective PPR are in place. The effort needs to be focused, and largely based on the existing STAR software for jet reconstruction. We need to effectively utilize the simulation datasets on the GRID, the Fastjet as well as qPYTHIA emulations in ALICE need to be available and used as the standard for jet algorithms and quenching simulations We will have in parallel a PPR writing team and PPR simulation team.

  35. Update on Identified particles in jets(hadro-chemistry, chirality)

  36. Particle identified jet measurementse.g.Sapeta/Wiedemann (Eur.Phys.J. C55 (2008) 293):The hadro-chemistry will change in medium medium modification medium modification

  37. ALICE primary track analysis using TPC rdE/dx Based on: tracking efficiency rdE/dx efficiency rdE/dx purity discuss rdE/dx issues tomorrow (Francesco Blanco)

  38. Efficiency and acceptance corrected spectra original efficiency & acceptance relative corrected error L k0 p k p

  39. Accuracy of measurement compared to Sapeta-Wiedemann predictions SW predictions (MLLA plus JEWEL-type medium modifications) Scaled PYTHIA reconstructed in ALICE jets (one LHC year Statistics)

  40. K/p ratio in STAR (p+p and A+A) STAR preliminary pT (GeV/c) K/ (Au+Au) >K/ (p+p) consistent with in-medium fragmentation (Sapeta-Wiedemann, arXiv:0707.3494) 41

  41. modified FF for identified particles(see Christina’s talk)

  42. Fries & Ko (arXiv:0711.0974):quark-gluon conversions

  43. STAR preliminary pT (GeV/c) Fries et al., arXiv:0801.0453 Jet-flavor conversions (A.Timmins, STAR, QM09) At RHIC the s-quark is supposed to show the effect as well. At ALICE s-quark production is too abundant though

  44. Formation Time of Resonances in LHC QGP (C. Markert et al., arXiv:0807.1509)

  45. hadrons/ resonances partonic medium side 1 near away side 2 partonic medium hadrons/ resonances Jet triggered quadrant analysis = very similar to a mixed d.o.f. system CDF underlying event analysis Probe chirality through resonances in jets(C. Markert et al., arXiv:0807.1509)

  46. e.g. STAR results:Trigger pT > 4GeV, f(1020) <pT>~ 0.9 GeV All angles In Jet-Plane Same Sidenear side 1 near away M inv (K+ K-) side 2 M inv (K+ K-) Out of Jet-Planeside1 + side2 In Jet-Plane Away Sideaway Systematic errors not included ! M inv (K+ K-) M inv (K+ K-) Probe chirality through resonances in jets(C. Markert et al., arXiv:0807.1509)

  47. Hadronic resonance reconstruction (example: ALICE-PPR K*)

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