1. 1 Heavy-Flavour Production in Nucleus-Nucleus Collisions: From RHIC to LHC André Mischke ERC-Starting Independent Research Group QGP - Utrecht Hirschegg 2010 Strongly Interacting Matter under Extreme Conditions 38 nd International Workshop on Gross Properties of Nuclei and Nuclear Excitations Hirschegg, Kleinwalsertal, Austria, January 17 - 23, 2010

2. Outline Introduction - heavy-flavour production and energy loss in QCD matter Total charm production cross section Nuclear modification factor Heavy-flavour azimuthal correlations Summary I will not talk about collectivity and Quarkonia Hirschegg - 22. Jan. 20102Andre Mischke (UU)

3. 3 Simplest way to establish the properties of a system - calibrated probe - calibrated interaction - suppression pattern tells about density profile Heavy-ion collisions - hard processes serve as calibrated probe (pQCD) - traversing through the medium and interact strongly - suppression provides density measure - General picture: energy loss via medium induced gluon radiation (Bremsstrahlung) p+p collision Au+Au collision Quark-Gluon Plasma after the collision Probing hot and dense QCD matter Nuclear modification factor: Hirschegg - 22. Jan. 2010Andre Mischke (UU)

4. central R AA data K.J. Eskola et al., Nucl. Phys. A747 (2005) 511 increasing density light charged hadrons, neutral pions photons Light hadron spectra at RHIC Strong suppression in central Au+Au collisions Suppression well described by energy loss models Medium density 30-50 times normal nuclear matter Surface bias effectively leads to saturation of R AA with density Limited sensitivity to the region of highest energy density 4

5. ~1~10 time scale (fm) “Thermalization of QGP” Heavy-flavour production  ~ h/2m Q Quarkonia melts and flow develops Primarily produced by gluon fusion in early stage of collision: production rates calculable in pQCD Sensitivity to initial state gluon distribution M. Gyulassy and Z. Lin, Phys. Rev. C51, 2177 (1995) Heavy quarks provide information about the hottest initial phase of the collision Higher penetrating power: m Q >> T c,  QCD 10 15 ~0.1 Hadronisation Parton energy loss Charm, PYTHIA 6.208 Heavy quark production 5

6. 6 Wicks et al, NPA784, 426 (2007) Energy loss of heavy quarks Bottom Charm Gluon radiation probability: parton hot and dense medium Probe deeper into the medium Dead-cone effect: gluon radiation suppressed at small angles (  < m Q /E Q ) Dokshitzer & Kharzeev, PLB 519, 199 (2001), hep-ph/0106202 Less energy loss:  E g >  E LQ >  E HQ Hirschegg - 22. Jan. 2010 Andre Mischke (UU)

7.  Semileptonic decay of charm and bottom mesons -first evidence for heavy-flavour particles F.W. Buesser et al. (CCRS), Nucl. Phys. B113, 189 (1976) -robust electron trigger -needs handle on photonic background  Full reconstruction of open charmed mesons -direct clean probe: signal in invariant mass distribution -difficulty: large combinatorial background; especially in a high multiplicity environment -event-mixing and/or vertex tracker needed single or non- photonic electron Detection of heavy-flavour particles Hirschegg - 22. Jan. 20107Andre Mischke (UU)

8. Spectra measured up to 10 GeV/c Integrated yield follows binary collision scaling Yield strongly suppressed at high p T for central Au+Au Au+Au 0-5% 40-80% p+p d+Au 10-40% Phys. Rev. Lett. 98 (2007) 192301 p+p Phys. Rev. Lett. 98, 172301 (2007) Au+Au Single electron spectra Hirschegg - 22. Jan. 20108Andre Mischke (UU)

9. d+Au 200 GeV PRL 94 (2005) 062301 Cu+Cu 200 GeV A. Shabetai, QM 2008 Au+Au 200 GeV arXiv:0805.0364 [nucl-ex] First identified open charmed mesons in heavy-ion collisions Current measurements limited to low-p T D 0 reconstruction in STAR Hirschegg - 22. Jan. 20109Andre Mischke (UU)

10. Use all possible signals - D 0 mesons - electrons - muons Charm cross section is well constrained - 90% of total cross section - direct measurement - D 0 mesons and muons constrain the low-p T region Charm cross section in STAR D0D0 electron muon Hirschegg - 22. Jan. 201010Andre Mischke (UU)

11. “Cocktail” of backgrounds constructed from measured background sources Comparison to charm, bottom and Drell-Yan from PYTHIA In good agreement with single electrons (PRL 103, 082002 (2009)) c dominant b dominant after subtraction of cocktail  cc = 518 ± 47(stat) ± 135(sys) ± 190(model)  b  bb = 3.9 ± 2.4(stat) +3/-2(sys)  b Di-electron measurement in PHENIX Phys. Lett. B670, 313 (2009) Hirschegg - 22. Jan. 201011Andre Mischke (UU)

12. Inclusive charm production cross section x4.5 x2 R. Vogt, Eur. Phys. J. Spec. Topic 155, 213 (2008) Factor ~2 difference between STAR and PHENIX; but consistency with NLO pQCD (large uncertainties; primarily from scale choice and parton density functions) Checks - removal of silicon vertex detectors (STAR) - better control over background contributions (PHENIX): 1/3 of single electrons are from J/  decays for p T > 5 GeV/c  up to 16% decrease in open heavy Cross section follows binary collision scaling Hirschegg - 22. Jan. 201012Andre Mischke (UU)

13. Open-charmed meson spectra from CDF Deviation of 50-100% at moderate and high-p T, but consistent within errors Theoretically not fully understood …even in pp collisions p p @ 1.96 TeV 5.8 pb -1 ¯ Hirschegg - 22. Jan. 201013Andre Mischke (UU)

14. Charm production cross section (cont’d) Large uncertainties  more data needed to constrain model parameters Parton spectra from pQCD input for energy loss models LHC: 7-10 TeV NLO pQCD, CTEQ6M parton densities R. Vogt, private communication, 2009 Hirschegg - 22. Jan. 2010 14Andre Mischke (UU)

15. First promising decay channels - D*  D 0  s, D 0  K , D +  K -  +  + - D,B  e + X ALICE has the capability to measure open charm down to p T = 0 in pp and p-Pb (1 GeV/c in Pb-Pb) ITS: impact parameter resolution better than 50  m for p T > 1.5 GeV/c Charm cross section in ALICE Hirschegg - 22. Jan. 2010 15Andre Mischke (UU)

16. MC@NLO LHC ? c cbar g g flavor creation (LO) gluon splitting (NLO) g g g g c cbar  0  MC@NLO LO PYTHIA like-sign e-K pairs 3 < p T < 7 GeV/c NLO processes: gluon splitting A. M., PLB 671, 361 (2009) Gluon jet energy (GeV) e-D 0 correlations at 200 GeV - away-side peak: Good agreement of peak shape between LO PYTHIA and MC@NLO - near-side: small gluon splitting contribution (  6.5%) Gluon splitting rate at RHIC consistent with MC@NLO Andre Mischke (UU)

17. D* - jet azimuthal correlations at LHC gluon splitting + flavour creation Full Pythia simulation, pp@10 TeV Different fragmentation characteristic: soft charm FF for gluon jets Results promising; more statistic needed jet axis D* gluon splitting (z < ~0.5) 300k jets, ~ 30 GeV  candidates  background ☐ signal Hirschegg - 22. Jan. 201017Andre Mischke (UU)

18. Nuclear modification factor Hirschegg - 22. Jan. 201018Andre Mischke (UU)

19. STAR PHENIX light hadrons Single electron R AA One of the most surprising results from RHIC Hirschegg - 22. Jan. 201019Andre Mischke (UU) Electron yield at high-p T stronger suppressed than expected Models implying D and B energy loss are inconclusive yet Large suppression requires extreme conditions; DGLV: dN g /dy = 3500

20. Hope? – AdS/CFT Heavy quarks lose momentum according to dp/dt = −p/  Q + stochastic Equilibration times  Q are roughly consistent with single electron R AA Hirschegg - 22. Jan. 201020Andre Mischke (UU)

21. Open heavy-flavour in Pb+Pb in ALICE m b = 4.8 GeV D 0  K  B  e+X 1 year @ nominal luminosity 10 7 (10 9 ) central Pb+Pb(p+p) events Open bottom reconstruction through displaced electrons S/B ≈ 10 % S/  (S+B) ≈ 40 D 0  K  Hirschegg - 22. Jan. 201021Andre Mischke (UU)

22. Mass hierarchy Colour charge dependence More details on heavy-flavour quenching mechanism R c AA /R b AA ratio different for pQCD and AdS/CFT Heavy-flavour energy loss at LHC Hirschegg - 22. Jan. 201022Andre Mischke (UU)

23. Single electron – D 0 correlations Hirschegg - 22. Jan. 201023Andre Mischke (UU)

24. compilation by A.M. 2009 FONLL has large uncertainty around the B  e / D  e crossing point (RHIC: 3 < p T < 10 GeV/c) Crossing point at LHC similar to that at RHIC Separate D  e and B  e contribution experimentally D and B contribution to single electrons M. Cacciari et al., PRL 95, 122001 (2005) − c  e ± + X (BR = 9.6%) -- b  e ± + X (BR = 10.86%) Hirschegg - 22. Jan. 201024Andre Mischke (UU)

25. 25 trigge r Away side: study in-medium D/B lose energy? conical emission? Near side: study D/B decay contribution to single electrons? Single electron-tagged correlations NLO pQCD: D/B meson crossing point is largely unknown M. Cacciari et al., PRL 95, 122001 (2005) Hirschegg - 22. Jan. 2010 Andre Mischke (UU) A. M., PLB 671, 361 (2009) PYTHIA, pp@200 GeV bottom dominant charm dominant

26. Electron-hadron correlations in STAR 26Andre Mischke (UU) B and D contributions comparable at p T > 5 GeV/c and consistent with FONLL Similar result from PHENIX (PRL 103, 082002) Bottom stronger suppressed than expected?

27. Single electron R AA at LHC T 0 = 1 GeV  0 = 0.15 fm/c # quark flavours: 2 Pyquen: Pb+Pb(5%)@5.5 TeV H. van Hees and R. Rapp, 2007 I. Vitev, A. Adil & H. van Hees, 2007 Pyquen Pythia afterburner Radiative (generalisation of BDMPS) and collisional energy loss (high-pT approximation) Hirschegg - 22. Jan. 201027Andre Mischke (UU)

28. Single electron – D 0 angular correlations 2 < p T trigger ele < 4 GeV/c Near side: B decays + gluon splitting charm Away side: charm flavour creation 900M events Pythia Pyquen Hirschegg - 22. Jan. 201028Andre Mischke (UU)

29. NLO processes bottom charm E. Norrbin and T. Sjostrand, Eur. Phys. J. C17, 137 (2000) Hirschegg - 22. Jan. 201029Andre Mischke (UU) GS charm + B decays GS charm only NLO processes (such as gluon splitting) become important at LHC

30.  (e, D 0 ): Near-side width and I AA 2 < p T trigger ele < 4 GeV/c I AA of near-side yield Hirschegg - 22. Jan. 201030Andre Mischke (UU) Broader peak for Pyquen than Pythia Suppression of D 0 yield for Pyquen Next: fragmentation function

31. Summary Heavy quarks are particularly good probes to study the properties of hot QCD matter (especially transport properties) RHIC (200 GeV) - energy loss of heavy quarks in the medium larger than expected  energy loss mechanism not fully understood yet (bottom stronger suppressed as expected ?) LHC (14 and 5.5 TeV) - pp data are important baseline measurements - inclusive charm production cross section & spectral shape: test pQCD - relevant for suppression measurements of Quarkonia states - NLO processes (like gluon splitting) become important: accessible by “charm content in jets” measurements - Jet-like heavy-flavour particle correlations: modification of the fragmentation function - First heavy-ion collisions anticipate in fall 2010 Exciting time ahead of us… Hirschegg - 22. Jan. 2010 31 Andre Mischke (UU) Pythia  pp Pyquen  PbPb

32. Backup Hirschegg - 22. Jan. 201032Andre Mischke (UU)

33. Ke3 decays (MC)  0 Dalitz and  conversion (MC) MC (  0 +Ke3) Data PHENIX Electromagnetic calorimeter and RICH at mid rapidity  p T < 5 GeV/c STAR ToF + TPC  p T < 4 GeV/c EMCal + TPC  p T > 1.5 GeV/c E/p Electron identification Hirschegg - 22. Jan. 201033Andre Mischke (UU)

34. Photonic electron background -   e + + e - (small for Phenix) -  0   + e + + e - - , etc. Phenix is almost material free  their background is highly reduced compared to STAR Background is subtracted by two independent techniques - very good consistency between them - converter method (1.68% X 0 ) - cocktail method STAR determines photonic background using invariant mass Phenix mass (GeV/c 2 ) e-e-  e+e+ e-e- dca Electron background sources STAR Hirschegg - 22. Jan. 201034Andre Mischke (UU)

35. Electron-hadron correlations in PHENIX arXiv:0903.4851 Use e-K invariant mass Statistics limited Mid-rapidity electron and forward- rapidity muon -> promissing… p+p Hirschegg - 22. Jan. 201035Andre Mischke (UU)

36. Charmonium contribution to single electrons New study takes J/  e ± +X contribution into account 1/3 of single electrons are from J/  decays for p T > 5 GeV/c  up to 16% decrease in open heavy But what is R AA of high-p T J/  ? Background contribution from K 0 s decays may also play a role (especially at low-p T )  under investigation 1/3 of e from J/  decays Hirschegg - 22. Jan. 201036Andre Mischke (UU)

37. Charm and bottom R AA Knowing R AA of single electrons and relative B contribution r B in p+p collisions, one can study R AA (b) as a function of R AA (c): Exclude original radiative calculation D and B measurements in A+A necessary p T > 5 GeV/c R AA = r B R AA (b) + (1-r B ) R AA (c) I: Djordjevic, Gyulassy, Vogt and Wicks, PLB 632 (2006) 81; dNg/dy = 1000 II: Adil and Vitev, PLB 649 (2007) 139 III: Hees, Mannarelli, Greco and Rapp, PRL 100 (2008) 192301 Hirschegg - 22. Jan. 201037Andre Mischke (UU)

38. Single electron-hadron correlations in Au+Au Away-side modification? Improved statistics and better background rejection needed Similar analysis in PHENIX STAR preliminary Hirschegg - 22. Jan. 201038Andre Mischke (UU)

39. UA1 jet reconstruction - cone size 0.4 - E thr = 10 GeV/c 2 D* in jets Hirschegg - 22. Jan. 201039Andre Mischke (UU)

40. Heavy-flavour production at LHC Heavy flavour copiously produced Charm and bottom yields (NLO pQCD predictions using MNR PDF) system,  s NN pp @ 14 TeV Pb+Pb (0-5%) @ 5.5 TeV 11.2 / 0.54.3 / 0.2 0.16 / 0.006115 / 4.6 Hirschegg - 22. Jan. 201040Andre Mischke (UU)

41. Kinematics for c-cbar pairs Δη ΔϕΔϕ ALICE (central barrel) acceptance Gluon splitting Hirschegg - 22. Jan. 201041Andre Mischke (UU)

42.  (e,D0) correlations for like-sign pairs Hirschegg - 22. Jan. 201042Andre Mischke (UU)

43. Near-side width and yield Hirschegg - 22. Jan. 201043Andre Mischke (UU)

44. Near-side I AA Hirschegg - 22. Jan. 201044Andre Mischke (UU)

45. Relevant heavy-flavour decay modes Charm charmed meson modes c  D 0 + X (BR = 56.5%) c  D + + X (BR = 23.2%) c  D *+ + X (BR = 23.5%) semileptonic channel c  e + + X (BR = 9.6%)  single (non-photonic) electron continuum Bottom charmed meson modes b  D 0 + X (BR = 59.6%) b  D - + X (BR = 23.5%) b  D *+ + X (BR = 17.3%) semileptonic channel b  e + + X (BR = 10.86%) Based on e + e - data from CLEO/ARGUS and LEP experiments Review of Particle Physics, C. Amstler et al. (Particle Data Group), Physics Letters B667, 1 (2008). Hirschegg - 22. Jan. 201045Andre Mischke (UU)

46.  Ldt = 5.10 26 cm -2 s -1 x 10 6 s 5.10 32 cm -2 PbPb run, 5.5 TeV N PbPb collisions = 2.10 9 collisions  Ldt dt = 3.10 30 cm -2 s -1 x 10 7 s 5.10 37 cm -2 for pp run, 14 TeV N pp collisions = 2.10 12 collisions Muon triggers: ~ 100% efficiency, ~ 1kHz Electron triggers: Bandwidth limitation N PbPb central = 2.10 8 collisions  Muon triggers: ~ 100% efficiency, < 1kHz Pb-Pb nominal run pp nominal run Electron triggers: ~ 50% efficiency of TRD L1 20 physics events per event Hadron triggers: N PbPb central = 2.10 7 collisions Hadron triggers: N pp minb = 2.10 9 collisions  LHC running conditions Andre Mischke (UU) 46 Hirschegg - 22. Jan. 2010