1. Heavy Ion Caf é 1 st meeting ~Experiment side~ K. Ozawa Univ. of Tokyo

2. 2006/12/9 Heavy Ion Cafe 2 Signatures of QGP K. Yagi, T. Hatsuda, and Y. Miake, “ Quark-Gluon Plasma ” (1) Average transverse momentum (2) Volume (3) Enhance of strangeness and charm (4) Enhance of anti-particles (5) Elliptic flow ( v 2 ) (6) Fluctuations conserved charges (7) Suppression of high-p T hadrons (8) Heavy quarkonium (9) Modification of light vector mesons (10) Thermal photons and dileptons (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

3. 2006/12/9 Heavy Ion Cafe 3 In Reality (1) Average transverse momentum (2) Volume (3) Enhance of strangeness and charm (4) Enhance of anti-particles (5) Elliptic flow ( v 2 ) (6) Fluctuations conserved charges (7) Suppression of high-p T hadrons (8) Heavy quarkonium (9) Modification of light vector mesons (10) Thermal photons and dileptons p T spectrum HBT Heavy flavor Particle ratio Elliptic flow Event-by-Event fluctuation Ratio to expectation (R AA ) J/and Y light vector mesons () Photons and electron pairs Near and away side Jet

4. 2006/12/9 Heavy Ion Cafe 4 Our activities and HI Cafe p T spectrum HBT Heavy flavor Particle ratio Elliptic flow Event-by-Event fluctuation Ratio to expectation (R AA ) J/and Y light vector mesons () Photons and electron pairs Near and away side Jet T. Chujo (M. Konno) A. Enokizono F. Kajihara and S. Sakai M. Konno (T. Chujo) H. Masui and S. Shimomura T. Nakamura T. Isobe T. Gunji and S. Oda Y. Nakamiya (and K. Ozawa) K. Ozawa 実際に解析をしている人に話してもらって、 各回にテーマを決めて、議論していきたい

5. 2006/12/9 Heavy Ion Cafe 5 Focus on Jet quenching At RHIC, we can use high pT particles to diagnose the medium. Measuring high p T particle yields: –Initial yields and p T distributions can be predicted from p+p measurements + pQCD + cold nuclear effects –Deviations can be attributed to the medium formed in A+A collisions High p T particles (leading particles of jets) as  0, can be measured in large BGs (dN ch /d ~ 700) A+A p+p

6. 2006/12/9 Heavy Ion Cafe 6 Observables Yield suppression by medium effects –Comparison with p+p Nuclear modification factor (R AA ) – Light (and Heavy) mesons Two (or three) particle correlation

7.  0,  measurements

8. 2006/12/9 Heavy Ion Cafe 8 T The p+p Reference Measurement at 200 GeV nucl-ex/0610036 00 

9. 2006/12/9 Heavy Ion Cafe 9 nucl-ex/0610036 Initial State Effects? New PHENIX paper on centrality dependence of  0 + in d+Au at 200 GeV d+Au as collision system to look for initial state effects => no strong initial state effects nucl-ex/0610036

10. 2006/12/9 Heavy Ion Cafe 10 Au+Au at 200 GeV   data from RHIC run 2004 p (GeV/c) T

11. Stronger Suppression for more central collision.  0 R AA is flat for all centrality for pT>5 GeV/c. Difference between  0 and charged increases for pT < 5 GeV/c. R AA at 200 GeV

12. 2006/12/9 Heavy Ion Cafe 12 Au+Au at 200 GeV ()  data from RHIC run 2004

13. 2006/12/9 Heavy Ion Cafe 13 R AA at 200 GeV ()  in Au+Au => Suppression by a factor of 5 in central events

14. 2006/12/9 Heavy Ion Cafe 14 R AA at 200 GeV Direct ,  0 and  in Au+Au –Direct  R AA with measured p+p reference! => R AA of  and  0 consistent, both show suppression => R AA of  is smaller than 1 at very high p T 0-10% central events

15. 2006/12/9 Heavy Ion Cafe 15 R AA at Different Energies Comparison of  0 in Cu+Cu at 200, 62.4, and 22.4 GeV –Measured the same collision species over a broad energy range Suppression gets larger with higher energies

16. 2006/12/9 Heavy Ion Cafe 16 R AA at Different system size Both behave same at mid central.

17. 2006/12/9 Heavy Ion Cafe 17 SPS and RHIC Same behavior for similar N part (63 at WA98, 67.8 at PHENIX) Blattnig parameterization used for WA98 data (S. Blattnig et. al., Phys.Rev. D62 (2000) 094030 / D. D’Enterria, Phys. Lett. B 596 (2004) 32))

18. 2006/12/9 Heavy Ion Cafe 18 Summary I Strong suppression up to 20 GeV suppression patternsof  0 and  are similar Clear Collision Energy dependence Consistent results for the same system size and the same energy Do these results mean jet energy loss in the medium?

19. 2006/12/9 Heavy Ion Cafe 19 Comparison with models C. Loizides hep-ph/0608133v2 I. Vitev W. Horowitz Use R AA to extract medium density: I. Vitev: 1000 < dN g /dy < 2000 W. Horowitz: 600 < dN g /dy < 1600 C. Loizides: 6 < < 24 GeV 2 /fm Statistical analysis to make optimal use of data Caveat: R AA folds geometry, energy loss and fragmentation

20. 2006/12/9 Heavy Ion Cafe 20 What do we learn from R AA ? ~15 GeV  E=15 GeV Energy loss distributions very different for BDMPS and GLV formalisms But R AA similar! Renk, Eskola, hep-ph/0610059 Wicks et al, nucl-th/0512076v2 BDMPS formalism GLV formalism Need more differential probes

21. 2006/12/9 Heavy Ion Cafe 21 R AA vs. Reaction Plane Au+Au collisions at 200GeV nucl-ex/0611007 In Plane Out of Plane In plane emission shows no energy loss in peripheral bins. 3<p T <5 GeV/c LL

22. 2006/12/9 Heavy Ion Cafe 22 R AA L  Dependence Au+Au collisions at 200GeV L  = matter thickness calculated in Glauber model Little/no energy loss for L   < 2 fm 0-10% 50-60% nucl-ex/0611007

23. 2006/12/9 Heavy Ion Cafe 23 p+p reference: Data (converter) for p T <1.6 [GeV/c] 1.71*FONLL for p T >1.6 [GeV/c] Suppression level is the almost same as  0 and  in high pT region Heavy Flavor

24. 2006/12/9 Heavy Ion Cafe 24 Summary II Several theoretical models can reproduce the experimental data. To investigate the origin of yield suppression, need more probes Reaction plane dependence of R AA is measured. Clear dependence on matter thickness is shown. Measurements for Heavy flavor show the similar results in high-p T.

25. Two or Three particle correlation

26. 2006/12/9 Heavy Ion Cafe 26  correlations at RHIC –“ Trigger-associated ” technique valuable for tagging jets in high-multiplicity environment (vs. jet-cone algorithms) –Probes the jet ’ s interaction with the QCD medium –Provides stringent test of energy-loss models  correlations  Trigger Associated Higher p T → Away-side suppression Pedestal&flow subtracted STAR, PRL 91 (2003) 072304 STAR, nucl-ex/0501016 Lower p T → Away-side enhancement p T (assoc) > 2 GeV/cp T (assoc) > 0.15 GeV/c 4 < p T (trig) < 6 GeV/c

27. 2006/12/9 Heavy Ion Cafe 27 Dijet assoc. yields (I AA ) vs. R AA STAR, Phys. Rev. Lett. 91 (2003) 072304 Near-side yields consistent with unity Away-side associated yields similar to R AA values I AA = Yield(0-5% Au+Au) Yield(d+Au) = Near-side I AA = Away-side I AA 8 < p T (trig) < 15 GeV/c

28. 2006/12/9 Heavy Ion Cafe 28 Centrality dependence

29. 2006/12/9 Heavy Ion Cafe 29 Z T Distribution Yield in |Δφ|>0.9 Z T = p T assoc /p T trig

30. 2006/12/9 Heavy Ion Cafe 30 I AA I AA = Yield(0-5% Au+Au) Yield(d+Au)

31. 2006/12/9 Heavy Ion Cafe 31 Shape analysis On this figure, Shape analysis is done.

32. 2006/12/9 Heavy Ion Cafe 32 Away side peak shape 3 fitting functions are used. Shifted peak is at almost constant 

33. 2006/12/9 Heavy Ion Cafe 33 Jet Functions (PHENIX) nucl-ex/0611019 rms, kurtosis and D also independent of p T of associated hadrons - poses challenge to color Cerenkov models D

34. 2006/12/9 Heavy Ion Cafe 34 Interpretations Mach Cone/Shock wave T. Renk, J. Ruppert Stöcker, Casseldery-Solana et al Cherenkov radiation Gluon rad+Sudakov A. Polosa, C. Salgado V. Koch, A. Majumder, X-N. Wang Many explanations possible, need more input to conclude Or large k T from radial flow or energy loss Fries, Armesto et al, Hwa Also: Vitev, Phys. Lett. B630 (2005)

35. 2006/12/9 Heavy Ion Cafe 35 3-particle correlations  13  12 0    13  12 0   Event by event deflection of jets Cone like structure in each event 3-particle  -  probes away-side structure: Distinguish event-by-event deflection vs conical (Mercedes) emission pattern 1: 3 < pt < 4 GeV/c (Jet Tag) 2,3: 1 < pt < 2 GeV/c,

36. 2006/12/9 Heavy Ion Cafe 36 Centrality 0-12%  12  13 Diagonal and Off-diagonal structures are suggestive of conical emission at an angle of about 1.45 radians in central Au+Au. Deflected Jet + Cone Cone Near Side Elongated Away Side Jet Jet - Flow Subtraction Result

37. 2006/12/9 Heavy Ion Cafe 37 3-Particle Correlations  High p T (1)Assoc. p T s (2,3) Same Side Away Side (3 particles from di-jet) + (2 from dijet + 1 other) PHENIX Preliminary *  *  12 *  13 *  _ = *  12 =   *=   *= 

38. 2006/12/9 Heavy Ion Cafe 38 Correlation Topologies Cone Jet Deflected Jet Normal Jet  * Azimuthal Section: (medium excitation) (scattered jet axis) (unmodified) PHENIX Simulation triples/trigger (A.U.) PHENIX Preliminary  *=   *=  PHENIX Preliminary

39. 2006/12/9 Heavy Ion Cafe 39 Near-Side Modification 0-10% Central Cu+Cu I AA = CY AA /CY PP 0-20% Central Au+Au Trigger p T

40. 2006/12/9 Heavy Ion Cafe 40 3<p t,trigger <4 GeV p t,assoc. >2 GeV Au+Au 0-10% preliminary Near side - Correlations Near-side long range correlation in  –STAR, nucl-ex/0509030 –near side “ ridge ” Phys. Rev. C73 (2006) 064907 mid-central AuAu p t < 2 GeV d+Au, 40-100%Au+Au, 0-5% 3 < p T (trig) < 6 GeV 2 < p T (assoc) < p T (trig) 0.8< p t < 4 GeV nucl-ex/0607003 See Poster by Ron Longacre  / √  ref

41. 2006/12/9 Heavy Ion Cafe 41 -Jet Correlations  Inclusive  -h  Decay  -h contribution (via  0 -hadron)  Direct  -h ! p+p collisions at 200 GeV

42. 2006/12/9 Heavy Ion Cafe 42 Comparison to Pythia

43. 2006/12/9 Heavy Ion Cafe 43 -Jet Correlations in AuAu Poster: M. Nguyen, N. Grau Talk: J. Jin (2.2.07)

44. 2006/12/9 Heavy Ion Cafe 44 Summary III We can see a clear away side suppression in two particle correlation. In addition, away side broadening exists. Analysis for three particle correlation is done. It suggests conical emission.