Recent Exciting Results from PHENIX

1. Recent Exciting Results from PHENIX Xiaochun He, Georgia State University For The PHENIX Collaboration • About PHENIX • QGP Characterization • Direct photon • Quarkonia • Summary and Outlook Outline ATHIC2012

2. PHENIX Collaboration 71 Institutions from 13 Countries ATHIC2012

3. PHENIX Run Summary • RHIC ran with many colliding species which range from p+p, d+Au, Au+Au, Cu+Cu, Cu+Au, U+U. • RHIC ran at variety center of energies. • RHIC beam scan program has started and will continue for years to come. Discovery and Diagnostic Period Beam-energy scan continues New era of heavy flavor physics Better knowledge on geometry Medium Characterization Started ATHIC2012

4. Central arms: hadrons, photons, Electrons: p > 0.2 GeV/c |y| < 0.35  Muon arms: muons at forward rapidity p > 2GeV/c 1.2 < |y| < 2.4  Centrality measurement: We use beam beam counters together with zero degree calorimeters Centrality is mapped to Npart (Ncol) using Glauber model PHENIX Detectors ATHIC2012

5. PHENIX has shed light on QGP! To be more accurate, light from QGP has arrived at PHENIX. • “Observation of direct-photon collective flow in Au+Au collisions at 200 GeV”, PRL 109, 122302 (2012), published on Sep 21, 2012 • “Measurement of direct photons on Au+Au collisions at 200 GeV”, PRL 109, 152302 (2012), published on Oct 12, 2012. What’s new in PHENIX? Direct photon ATHIC2012

6. Direct Photon RAA PRL 109, 152302 (2012) RAA is found to be consistent with unit for all centralities over the entire measured pT range! ATHIC2012

7. Direct Photon RAA Comparison with Model Calculations PRL 109, 152302 (2012) The model calculations that account for modifications of initial direct photon production due to modified PDF’s in Au and the different isospin effects show modest deviation from unit. They are consistent with data. ATHIC2012

8. Direct Photon Flow in Au+Au PRL 109, 122302 (2012) The results from two independent reaction plane detectors (BBC and RXN) are very consistent, especially at pT < 5 GeV/c. At larger pT, the effects of reaction plane detector efficiencies show mild differences but don’t change the physics conclusion. ATHIC2012

9. Virtual vs Real Photon Flow PRL 109, 122302 (2012) We observed a substantial flow at low pT region comparable to the hadron flow. However, in contrast to hadrons, the direct-g v2 rapidly decreased with pT, and for pT > 5 GeV/c, it is consistent with zero. ATHIC2012

10. Since Matsui and Satz proposed the idea of using J/ysuppression as a signal for QGP formation in 1986, lots of efforts have been put both in experiments and in theories in order to characterize the matter properties at extreme hot and dense conditions. After 26 years, the situation is not as clear as we have hoped for. Recent results from PHENIX at 39 and 62.4 GeV in Au+Au collisions add more twists! It is imperative to disentangle the interplay among cold nuclear effects, QGP color screening, and possible regeneration. What’s new in PHENIX? Quarkonia (Focusing on J/y) ATHIC2012

11. J/y Production vs Centrality Existing Puzzle Forward rapidity Mid rapidity Npart dependence of J/ RAA: less suppression at LHC compared to at RHIC in central collisions. ATHIC2012

12. J/y Production vs Energy aiXrv: 1208.2251 ATHIC2012

13. Comparison with Theory aiXrv: 1208.2251 ATHIC2012

14. Quantify Cold Nuclear Matter Effects • High statistics d+Au data set taken in 2008 • J/ψ at backward, mid, and forward rapidities as a function of centrality, y, and (new) pT. • (new) ψ' at midrapidity as a function of centrality. • (new) χc at midrapidity • Upsilon at backward, mid (coming soon), and forward rapidities. ATHIC2012

15. Centrality Dependence 60-88% Au d RdAu consistent with 1 at all pT for peripheral collisions D McGlinchey - QM2012

16. Centrality Dependence 40-60% Au d Increasing suppression at low-pT when moving to central events D McGlinchey - QM2012

17. Centrality Dependence 20-40% Au d Increasing suppression at low-pT when moving to central events D McGlinchey - QM2012

18. Centrality Dependence 0-20% Au d Increasing suppression at low-pT when moving to central events Enhancement at high-pT at backward rapidity Implies RAA(CNM) ³ 1 at high-pT in Au+Au D McGlinchey - QM2012

19. y’ RdAu • Strong suppression with increasing Ncoll • Centrality dependence of the suppression is even stronger at the mid-rapidity. ATHIC2012

20. Cu+Au(Controlled Geometry) ATHIC2012

21. New era of heavy flavor physics at RHIC has started. A outlook! Open Heavy flavor ATHIC2012

22. Need to Know the Baseline Open heavy flavor measurements in p+p collisions NEW Charm cross section follows Nbin scaling from p+p to Au+Au collisions ATHIC2012

23. Help is on the way – (F)VTX VTX+FVTX New silicon vertex trackers: VTX ( commissioned in 2011) and FVTX (commissioned 2012) ATHIC2012

24. More Outlook • sPHENIX offers a unique opportunity to study jet-medium physics over a wide range of collision energies not accessible to LHC . • This upgrade will provide essential complementary physics to the beam energy scan currently underway at RHIC. arXiv:1207.6378 ATHIC2012

25. The Concept 10 GeV/c pion showering in the hadroniccalorimeter ATHIC2012

26. Direct-g RAA is near zero Summary Thermal-g flows Direct-g does not flow J/y is suppressed in numerous sys. Need to pin down interplay effects. Separating b and c Is a reality in PHENIX Future jet- Tomography Is on horizon ATHIC2012

27. Thank you ATHIC2012

28. Direct photons in d+Au and Au+Au arXiv:1208.1234 B. Sahlmueler Parallel 3C RdA is consistent with unity • Large excess of γ observed in Au+Au is not due to initial state effects • Reinforce interpretation of the Au+Au excess as thermal radiation from the QGP QM12, Washington, Aug. 13-18, 2012

29. Direct photon v2 Phys. Rev. Lett. 109, 122302 (2012) arXiv:1105.4126 • Large v2 at pT < 4 GeV/c where thermal photons dominate • v2 consistent with 0 at high pT where prompt photons domininate Au+Au √sNN = 200 GeV minimum bias • Very surprising result: large v2 implies late emission whereas thermal radiation implies early emission • Models have difficulties in reproducing simultaneously yield and v2 of photons Poster 282 M. Csanad

30. Direct photon v2 via external conversion Poster 64, R. Petti External conversions (PHENIX preliminary) arXiv:1105.4126 • Independent analysis • Different systematics • pT range extended down to 0.5 GeV/c • Two independent and consistent results • Important confirmation of previous v2 results

31. Newest Heavy Ion Run (Run-12) at RHIC U+U andCu+Au ATHIC2012

32. Global Properties ATHIC2012

33. U+U vsAu+Au ATHIC2012

34. J/y in CNM Phys. Rev. Lett. 107 (2011) 142301 J/ψ are suppressed at all rapidities, in all centralities. Model using shadowing (EPS09) + sbr Qualitatively matches what we see, but cannot simultaneously capture the rapidity and centrality dependence. arxiv:1010.1246 Au d ATHIC2012

35. J/y vs. pT(peripheral and central) Weak modification in peripheral; shadowing reproduces fairly well, except to strong at forward rapidity Au d -2.2 < y < -1.2 |y| < 0.35 1.2 < y < 2.2 Stronger modification in central; shadowing alone cannot reproduce the trend Backward rapidity: high pT EMC effect suppression Need Cronin-like scattering or some other physics! ATHIC2012

36. J/y vs. pT(0-100% centrality) Au d RdAu rises out to pT~5 GeV/c at all rapidities. Largest disagreement with models is at backward rapidity. Shadowing + sbr model (no Cronin) does not match the qualitative trend. Model by Kopeliovich et al. includes Cronin and sbr prediction, qualitatively matches the pT shape. arXiv:1204.0777, submitted to Phys Rev C ATHIC2012