Recent Heavy Ion Results from PHENIX

1. Recent Heavy Ion Results from PHENIX Carla M Vale Brookhaven National Laboratory for the PHENIX Collaboration September 23 2010

2. Single spectra From 0 to multiple particle ID Expand to higher pT v2 at high pT and azimuthal dependence of RAA Two-particle correlations Expand range of trigger and associate Azimuthal dependence -hadron correlations Outline Overview of PHENIX’s experimental contributions towards the understanding of energy loss, focusing on recent publications and results • Jet reconstruction • Spectra • RAA PHENIX Results, Carla M Vale

3. PHENIX in 2010 Crossed the Petabyte frontier! Final run with HBD and RXNP Installation of SVX now ongoing PHENIX Results, Carla M Vale

4. Single hadron spectra PHENIX Results, Carla M Vale

5. PHENIX RAA for identified particles The variety and precision of results keep expanding, revealing interesting features • 0,  • photons • heavy flavor from e± • K±, ,  PHENIX Results, Carla M Vale

6. RAA at high pT is well described by several theoretical frameworks, with differing assumptions/ingredients The 0 dilemma Solution: Add more data to the picture, going from simpler to more differential PHENIX Results, Carla M Vale

7. Extend experimental range:  At pT ~ 15 GeV and above, 0 measurement limited by systematic uncertainties due to merging of the two photon showers in the calorimeter; for , this is not the case until pT ~ 50 GeV PRC82, 011902 (2010) arXiv:1005.4916 Trend for  is consistent with 0; Linear fits indicate RAA slowly rises or is flat with pT; Measurement is still statistically limited: future improvements PHENIX Results, Carla M Vale

8. RAA for  arXiv:1004.3532 • Suppression for  starts out weaker than for 0 and , but approaches it at high pT; K± at low pT seem to follow same trend as  • Npart scaling seen for Cu+Cu (not shown) • Binary scaling applies in d+Au: no evidence of cold nuclear matter effects (not shown) PHENIX Results, Carla M Vale

9. Azimuthal asymmetry PHENIX Results, Carla M Vale

10. 0 v2 at high pT arXiv:1006.3740 • Non-zero v2 even at high pT • The measured v2 at high pT is not a result of the hydrodynamical anisotropy, but arises from the dependence of the energy loss on the amount of medium that the partons have to traverse  look at RAA () PHENIX Results, Carla M Vale

11. RAA in-plane vs. out-of-plane pT RAA Npart • Out-of plane RAA nearly flat with centrality at low pT • In- and out-of-plane converge at high-pT (~10GeV/c) PHENIX Results, Carla M Vale

12. Comparing with models Stronger path length dependence  better agreement HT, ASW, AMY comparisons: S.Bass et al in arXiv:0808.0908 AdS/CFT: Marquet and Renk in arXiv:0908.0880 PHENIX Results, Carla M Vale

13. Di-hadron PHENIX Results, Carla M Vale

14. 0-hadron correlations PRL104, 252301 (2010) arXiv:1002.1077 • Near side: • width matches p+p, yield enhanced at low pT • Away side: • low pT: broad non-gaussian peak • for high trigger and associated pT, away side peak is suppressed but shape is consistent with p+p PHENIX Results, Carla M Vale

15. Away-side IAA At high pT, head region and full away side IAA consistent: no shape modification IAA larger than 0 RAA: surface bias balanced by away-side spectrum being softer than single inclusive hadron PHENIX Results, Carla M Vale

16. 0-h azimuthal dependence Check how per-trigger yields change as a function of the angle between trigger and the reaction plane: test path-length dependence PHENIX Results, Carla M Vale

17. Near side yield Near side yields nearly constant when going from in- to out-of-plane PHENIX Results, Carla M Vale

18. Away side yield Away side yields drop from in-plane to out-of-plane: clear path-length dependence PHENIX Results, Carla M Vale

19. -jet PHENIX Results, Carla M Vale

20. Direct  - h correlations • g insensitive to strong interaction  no surface bias, can probe the entire geometry • well calibrated, Eg ~ Ejet (to leading order) PHENIX Results, Carla M Vale

21. -h away-side Same level of suppression as in 0 RAA and 0-h IAA PHENIX Results, Carla M Vale

22. Fragmentation functions in p+p and Au+Au p+p slope: 6.89  0.64 Au+Au slope: 9.49  1.37 PHENIX Results, Carla M Vale

23. Jet reconstruction PHENIX Results, Carla M Vale

24. Full jet reconstruction • Gaussian filter method: cone-like, but no hard angular cut-off • Analysis performed in p+p and Cu+Cu events • Fake rejection essential in heavy ion environment PHENIX Results, Carla M Vale

25. Jet spectra in p+p Spectra and fragmentation functions in p+p consistent with NLO and PYHIA PHENIX Results, Carla M Vale

26. Jet RAA in Cu+Cu Similar to 0 RAA value Consistent with flat pT dependence PHENIX Results, Carla M Vale

27. Summary & Outlook • First decade of RHIC running completed • Shifting from making new measurements to increasing precision and constraining theory • Putting together a full picture of energy loss through developments in several directions: higher pT, (multi-)particle ID, correlations and full jet reconstruction • HBD Au+Au run this year: results coming soon • About to start the era of upgrades • Silicon Vertex detector installation ongoing • FVTX to follow • Already planning for the next decade… PHENIX Results, Carla M Vale

28. Counts per 2.5 GeV bin in 50B AuAu Events Central Arm upgrade: 2,  = 1 SVX +FVTX + More Si Tracking layers + Compact EMCal + Solenoidal Magnet + Hcal + High speed/bandwidth DAQ NLO pQCD (W. Vogelsang) CTEQ6M5, DSS FF pp @ 200 GeV |h|<1.0 q,g jets Direct g Fragmentation g p0(assume RAA = 0.2) p0 GEANT4: Q-Pythia Dijet Event Photons Jets The Future: sPHENIX PHENIX Results, Carla M Vale