1. Heavy Flavor measurements with the ALICE EMCAL detector Mark Heinz Yale University EMCAL Meeting, Nantes, July 16, 2008

2. Mark HeinzEMCAL Meeting Nantes, July 20082 Outline  Heavy flavor physics with EMCAL  The Essentials Simulation Status at CD-2 What needs to be done for PPR 2008. B-tagging algorithms  The Optionals (“exciting future measurements”)  Outlook & Summary

3. Mark HeinzEMCAL Meeting Nantes, July 20083 Testing pQCD  Current theoretical estimates for bottom and charm production at LHC still have large uncertainties.  Charm x-section measurements disagree at RHIC for STAR and PHENIX by a significant amount. Theory Uncertainties: NLO pQCD, pp,  s = 14 TeV CERN/LHCC 2005-014, hep-ph/0601164 Large uncertainty in cross-sections

4. Mark HeinzEMCAL Meeting Nantes, July 20084 Medium effects on Heavy quarks  Parton energy loss in the medium Magnitude of Dead-cone effect and quark mass dependence within a limited kinematical range  Quark vs gluon energy loss in the medium (Color Factors) B-jets constitute a very pure sample of quark jets.  Distinction between AdS/CFT and pQCD? WHDG, nucl-th/0512076

5. The Essentials

6. Mark HeinzEMCAL Meeting Nantes, July 20086 Annual Heavy Flavor electrons vs backgrounds  More detailed rate-plot for 1 year of Pb+Pb running in EMCAL acceptance.

7. Mark HeinzEMCAL Meeting Nantes, July 20087 Electron/Hadron ratio  We will need to identify high-pt (>10 GeV/c) electrons. How large are the hadron backgrounds?  Track-EMCAL cluster matching Max. track-matching efficiency for electrons in Hijing events with tuned EMCAL cuts is ~90% up to 30 GeV/c ~400

8. Mark HeinzEMCAL Meeting Nantes, July 20088 EMCAL PID (electron vs hadron)  Using matched cluster track-pairs we determine the momentum/Energy (p/E) ratio of tracks Resolution of p/E peak for two different energies Electrons Pions

9. Mark HeinzEMCAL Meeting Nantes, July 20089 Background Electron Sources  Full Simulation of photons in ALIROOT v4-06 include newer GEANT model of TOF-Geometry (additional material) <10% convert before TRD/TOF Integrated over area of EMCAL Start of EMCAL: 454cm PYTHIA+GEANT Simulation of mono-energetic photons

10. Mark HeinzEMCAL Meeting Nantes, July 200810 Statistical reach of B-jets  By triggering on high-pt electrons tightly correlated with the b-jet (Cone dR<0.2) we are biasing our sample to high pt B-jets.  For 70 GeV/c B-jets we obtain about a factor 5 more statistics using a electron trigger  A sample of several hundred B-jets with momenta up to 80 Gev/c will be acquired during 1 month Pb-Pb running

11. Mark HeinzEMCAL Meeting Nantes, July 200811 B-tag: A method - Displaced Vertex Method  The method pursued here has previously been used by CDF to identify secondary vertices from semi-leptonic decays.  Breakdown of method: Find a high-pt electron trigger particle in EMCAL Pair with all charged hadrons within a cone of radius dR. Reconstruct “approximate” (average between B-D decay) secondary vertex and apply more cuts to reduce backgrounds from other leptonic decays. Plot L xy distribution and obtain B- contribution from positive/negative imbalance D0D0 B- e- K  /e P e+K r PrimVtx SecVtx L xy = r.p e+k / |p e+k | L xy CDF Phys.Rev.D66 (2002))

12. Mark HeinzEMCAL Meeting Nantes, July 200812 Charm backgrounds (dominant source)  Due to the shorter life-time secondary vertices will naturally have a narrower L xy distribution.  To further reduce displaced vertices from charm by cutting on the electron-hadron M_inv. M e+h < M + M e + M h = M D ~ 1.9 GeV Beauty (after cut) Charm (after cut)

13. Mark HeinzEMCAL Meeting Nantes, July 200813 Signal vs. Backgrounds  Electron p T -cut > 10 GeV/c  Min. 6 ITS-hits on both electron/hadron track  Inv mass of (elec-kaon) mass > 1.7 GeV  Pair DCA < 200  m  B-Tag = |L xy | > 600  m Backgrounds Cuts used for analysis

14. Mark HeinzEMCAL Meeting Nantes, July 200814 Efficiencies & Rejection All sources B-jets Dalitz Conversions Charm B-jets More stats needed, higher p T

15. Mark HeinzEMCAL Meeting Nantes, July 200815 W backgrounds   pTpT pTpT EMCAL Acceptance B-jet electronsW electrons So far only a qualitative look ~10x higher stats

16. Mark HeinzEMCAL Meeting Nantes, July 200816 DVM Comparison: B-jet vs W B-jetsW Standard cuts Standard cuts + M inv > 1.7 GeV (charm rejection) Standard cuts + M inv > 1.7 GeV + Max ITS-hits Blue = Signal = right - left

17. Mark HeinzEMCAL Meeting Nantes, July 200817 Displaced Vertex simulation results After applying DVM cuts the signal efficiency is ~30-40%, whereas the backgrounds are factor ~100 suppressed. Electrons from all sources (before DVM method) Electrons from all sources (after DVM method)

18. What needs to be done ? (short-term until PPR)

19. Mark HeinzEMCAL Meeting Nantes, July 200819 PPR 2008  Physics Performance Report (PPR) will be prepared for EMCAL for end of 2008. Effort lead by Rene Bellwied 6 different topical working groups formed  All current studies need to be upgraded with more statistics and current version of AliRoot  Electron-Hadron-ID needs to be checked with results from 2007 Testbeam to ensure stability

20. Mark HeinzEMCAL Meeting Nantes, July 200820 Preliminary work matrix (PPR) TaskToolsManpowerStatistics Revisit rates (higher stats) PYTHIA + Material --- kinematics info 0.5 person100k x 15 jet p T bins Re-check e-ID (track- matching, p/E) PYTHIA/HIJING + Full simulation 0.5 person Single e,  0 10k x ~10 p T ranges 100k x 15 jet p T bins + 10k HIJING bkg Electron and E-Jet trigger (rates/bkg) PYTHIA/HIJING + AliEMCALTrigger, HLT Trigger Group? 100k x 15 jet p T bins + 10k HIJING bkg Electron spectra/R AA (e  B/D corresp., compare to TPC and TPC+TRD) PYTHIA + Full simulation 1 person100k x 15 jet p T bins 100k x ~5 p Thard bins each of MSEL4 and MSEL5 D/B Spectra/R AA (e+D, J/Psi+K, mis-ID) PYTHIA + Full simulation 1-2 people100k x 15 jet p T bins 100k x ~5 p Thard bins each of MSEL4 and MSEL5 B-jets (DVM,W,JETAN reco, FF, other tag methods) PYTHIA/HIJING + Full simulation 2-3 people100k x ~5 p Thard bins each of MSEL4 and MSEL5 50-100k W-boson decays 10k HIJING bkg

21. Mark HeinzEMCAL Meeting Nantes, July 200821 Non-photonic Electron R-AA  Most importantly compare to measurements in Alice with TPC and TPC+TRD to identify a kinematic regime where EMCAL is unique. How will the EMCAL triggering help enhance our yields ?  Determine photonic conversion probabilities and develop conversion vertex rejection methods ? non phot. el.

22. Mark HeinzEMCAL Meeting Nantes, July 200822 B-tagging  Start of with jet-finding algorithm  A brief overview of some different algorithms for b- tagging (see studies by CDF,D0,CMS…) Secondary, displaced vertex type algorithm (Karlsruhe) Soft lepton tag (INFN) Track-impact parameter based (INFN PISA)  In the end several tags can always be combined in a linear discriminant (LDA) method.

23. Mark HeinzEMCAL Meeting Nantes, July 200823 CMS Secondary Vertex Tracker (Weiser et al.) CMS Note 2006/14

24. Mark HeinzEMCAL Meeting Nantes, July 200824 B-Tagging: Track Impact Parameter Based  More details in CMS-Note (Rizzi et al, INFN Pisa) 2006/19 Tagging Variables First studies were started in Alice by Bonvini, Antinori et al (PWG3, Sep 2007)

25. “Exciting new measurements” My personal selection of QM 08 high-lights  High-Pt J/   Electron-Charm correlations

26. Mark HeinzEMCAL Meeting Nantes, July 200826 Electron-Charm correlations

27. Mark HeinzEMCAL Meeting Nantes, July 200827 (K  ) invariant mass distribution w/o electron trigger w/ non-photonic electron trigger Clear D 0 signal w/o background subtraction

28. Mark HeinzEMCAL Meeting Nantes, July 200828 Electron – Charm correlations (2) A. Mischke (HP 2008)

29. Mark HeinzEMCAL Meeting Nantes, July 200829 J/  at high-p T Zebo Tang (STAR) QM08 Investigate heavy quarkonium production mechanism and hadronization In p+p collision Gluon fusion Charm fragmentation Feed down In heavy ion collision Gluon energy loss Heavy quark energy loss Hot-wind dissociation in QGP

30. Mark HeinzEMCAL Meeting Nantes, July 200830 High-p T J/  Dissociation or not? Double the p T range to 10GeV/c Consistent with no suppression at high p T : R AA (p T >5 GeV/c) = 0.9±0.2 Low p T : R AA (pT<4 GeV/c) = ~0.5 Indicates R AA increase from low p T to high p T Most models expect a decrease R AA at high p T : AdS/CFT: H. Liu, K. Rajagopal and U.A. Wiedemann, PRL 98, 182301(2007) and hep-ph/0607062 Two Component Approach: X. Zhao and R. Rapp, hep-ph/07122407 private communication Zebo Tang (STAR), QM08

31. Mark HeinzEMCAL Meeting Nantes, July 200831 J/Psi – hadron correlations

32. Mark HeinzEMCAL Meeting Nantes, July 200832 J/Psi – hadron correlations Zebo Tang (STAR), QM08

33. Mark HeinzEMCAL Meeting Nantes, July 200833 Summary  Baseline studies were performed for US CD-2 document in Dec 2007 Need to be updated and improved  EMCAL Physics Performance Report (PPR) is next deadline Structure & meetings are in place  We need to continue to watch new results from RHIC More studies of other observables need to be started now with a goal of having simulations beyond the PPR

34. Mark HeinzEMCAL Meeting Nantes, July 200834  Backup

35. Mark HeinzEMCAL Meeting Nantes, July 200835 Z-Boson decay into electrons Dielectron decays:  Main source of background are jets from misidentified pions.  An isolation cut is mandatory. A track i is rejected if it is found a track j with p t > 2 GeV/c |  |  0.1 && |  |  0.1 rad Zaida., HP2008 R. Bailhache et al: Proc. QM08,

36. Mark HeinzEMCAL Meeting Nantes, July 200836 D0 measurement of weak boson PRL 1995

37. Mark HeinzEMCAL Meeting Nantes, July 200837 Z/W predictions from Tevatron toLHC  Probe PDF’s