1. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo Baryon anomaly at RHIC Tatsuya Chujo (University of Tsukuba)

2. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 2 Baryon/Meson anomaly PHENIX: PRL 91, 172301 (2003), PRC 69, 034909 (2004), PRC 74, 024904 (2006) “Baryon anomaly (or enhancement) at RHIC”. In Au+Au  s NN = 200 GeV central collisions: R CP (or R AA ) Pions: Strong suppression of yields above p T ~ 2 GeV/c, due to jet quenching effect. Protons: No suppression for at intermediate p T (2-5 GeV/c). p/  and  p/  ratios More (anti) baryons than pions at intermediate p T (2-5 GeV/c). Strong centrality dependence. Inspired extensive theoretical works to explain the data.

3. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 3 R cp from Recombination R cp splitting between baryons and mesons comes naturally in the recombination approach. Hwa, Yang Recombination + Fragmentation is needed to reproduce identified spectra and R cp measurements at higher p T. Fries, Muller, Nonaka, Bass R.J. Fries, et al., Phys. Rev. Lett. 90 202303 (2003). R. C. Hwa, et al., Phys. Rev. C 70, 024905 (2004). V. Greco, et al., Phys. Rev. C 68, 034904(2003).

4. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 4 Intermediate p T : “Hard” pions vs. “Soft” protons (mass effect)  K p Interplay between “ Soft ” and “ Hard ” Crossover: 1.8 GeV/c  , 2.6 GeV/c  K, 3.8 GeV/c  p T.Hirano, Y.Nara, Phys.Rev.C69,034908(2004) Hydro+Jet R AA

5. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 5  →K + K - R AA  R AA looks like the   rather than the proton, even if mass(  ) ~ mass(p)! Suggested that it’s not the mass effect, but baryon/meson effect.

6. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 6 Particle type dep. of elliptic flow (v 2 )

7. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 7 Quark Recombination on v 2 Number of constituent quark scaling (n =2 for mesons, n =3 for baryons) works. Suggested that pressure developed at quark level, not hadrons.

8. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 8 PHENIX White Paper (2004-2005) says…

9. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 9 Since then… Detector upgrades: –PHENIX: Aerogel Cherenkov, TOF.W –STAR: MRPC TOF (on-going) High statistics data: –Au+Au 200 GeV (2004) –Cu+Cu 200 GeV (2005) –p+p 200 GeV (2005,2006) Lower beam energy data: –Au+Au 62 GeV (2004) –Cu+Cu 22, 62 GeV (2005) –p+p 62 GeV (2006)

10. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 10 Outline Current understanding of baryon production at intermediate p T at RHIC from the most recent data (spectra and v 2 ). 1.Onset of baryon enhancement: Beam energy dependence of  p/ , R AA (p,  p,  ). Connection to the SPS energy. 2.Transition from soft to hard process: High p T protons and pions spectra, p/ , R AA (R cp ) in Au+Au/Cu+Cu 200 GeV. 3.Scaling properties of v 2 and quark degrees of freedom: Quark number (NCQ) scaling vs. KE T /n scaling (Au+Au/Cu+Cu).  meson v 2. Where is the breaking point of NCQ scaling?

11. 1.  s dependence (focused on antiprotons)

12. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 12 New PID spectra at lower  s NN New datasets are now available! Let’s look at  p/   ratio as a function of  s NN in p+p, Cu+Cu, Au+Au.

13. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 13 p+p 62.4 GeV, set the baseline for HI data. New PHENIX data agrees with ISR data. * No weak decay feed-down correction applied.  s dep. of  p/  - ratio (central)

14. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 14 Cu+Cu 22.5 GeV,  p/   ratio in central agrees with p+p.  s dep. of  p/  - ratio (central)

15. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 15 Cu+Cu 62.4 GeV,  p/   ratio larger than those in p+p and Cu+Cu 22.5 GeV.  s dep. of  p/  - ratio (central)

16. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 16 Cu+Cu 200 GeV, similar to those in Cu+Cu 62.4 GeV.  s dep. of  p/  - ratio (central)

17. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 17 Au+Au 62 GeV,  p/  - is unchanged from Cu+Cu 200 GeV  s dep. of  p/  - ratio (central)

18. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 18 Au+Au 200 GeV,  p/  - is enhanced.  s dep. of  p/  - ratio (central)

19. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 19 Peripheral collisions for all systems Conversing to the same line  s dep. of  p/  - ratio (peripheral)

20. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 20 * No weak decay feed-down correction applied. In 22.5 GeV Cu+Cu: weak centrality dependence,  p/  - ratios are ~0.3-0.4 at p T = 2 GeV/c, which is close to the value in p+p. In 62.4 GeV Cu+Cu:  p/  - ratio in central collisions reaches R=~0.6 at p T = 2 GeV/c, decreasing towards the peripheral events. Centrality dep. of  p/  - (22 GeV vs. 62 GeV) 0.3

21. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 21 0 1.0 2.0 3.0 p T (GeV/c) Comparison with SPS data 0.25 Pb+Pb 17.2 GeV (central) T. Schuster, A. Laszlo (NA49) nucl-ex/0606005 SPS Pb+Pb: consistent with Cu+Cu 22.5 GeV  p/ .

22. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 22 Increasing as a function of  s. Indicates the onset of baryon enhancement is in between 22 GeV and 62 GeV. * No weak decay feed-down correction applied.  p/  - ratio (central): summary

23. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 23  s NN dep. R AA for antiprotons (by ISR fit) Used ISR data at 23 GeV and 63 GeV (Alper. NPB 100, 237) for p+p reference. Similar R AA for all three systems. * Note: p+p 62.4 GeV p+p data has been measured by PHENIX, still working on the trigger bias and cross section seen in the detector. Here we use ISR fit to obtain R AA. * No weak decay feed-down correction applied.

24. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 24  s NN dep. R AA for charged pions (by ISR fit) Error notations: - Error bars: statistical error for HI spectra - Boxes: 1) sys. error for p+p reference. 2) sys. error for HI spectra. - Lines: N coll error (1 .) Used ISR fit (nucl- ex/0411049, D. d’Enteria) for p+p parameterization. Moderate suppression for Au+Au 62.4 GeV. Greater than unity for Cu+Cu 62/22 GeV (p T > 2.0 GeV/c). * No weak decay feed-down correction applied.

25. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 25  0 at 22.5 GeV (centrality dep.) Little centrality dependence Baldo Sahlmüller (QM06)

26. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 26 SPS (17 GeV) vs. RHIC (22 GeV) 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)) Baldo Sahlmüller (QM06)

27. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 27  0 R AA vs.  s NN D. d’Enterria, nucl-ex/0504001

28. 2. High p T protons,  and transition from soft to hard process

29. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 29 -p/  (  p/  ) ratios turn over at intermediate p T, and be close to the value of fragmentation expectation at high p T. - Strong centrality dependence. -Comparing with p+p data: indicating a transition from soft to hard at intermediate p T. - No weak decay feed-down correction applied. - p+p data (PRC 74, 024904 (2006)) p/  in Au+Au 200 GeV Masahiro Konno (QM06)

30. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 30 - Baryon enhancement in Cu+Cu at 200 GeV too. - p T dependence in Cu+Cu is similar to that in Au+Au. p/  in Cu+Cu 200 GeV PHENIX preliminary Masahiro Konno (QM06)

31. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 31 Transition from soft to hard STAR, Phys. Rev. Lett. 97 (2006) 152301 p/  PHENIX preliminary Masahiro Konno (QM06) Baryon enhancement occurs in the p T region from 1.5-5.0 GeV/c. Recombination modes with hard component reproduce the data.

32. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 32 STAR, Phys. Rev. Lett. 97 (2006) 152301 M. Konno (HQ06) R cp in Au+Au 200 GeV R cp R cp data also show that baryon enhancement is in the limited pT range (p T = 1.5 - 5.0 GeV/c).

33. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 33 PHENIX preliminary R AA (Au+Au 200 GeV) Masahiro Konno (QM06)

34. 3. Scaling properties of v 2

35. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 35 200 GeV Au+Au min. bias (0 – 80%) NCQ Scaling for v 2 Deviation from perfect scaling:  Imperfections of recombination approach?  Wrong scaling variable?  Different hadronization mechanism?  Gluon degrees of freedom plays a role? B. Müller, R. Fries, S Bass, Phys. Lett. B618, 77-83 (2005) P. Sorensen, QM2005 PHENIX o PHENIX

36. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 36  Essence: all particles originate from a common velocity field.  Elliptic flow scales with KE T up to KE T ~1 GeV for all particle types, which indicates hydrodynamic behavior.  Clear Baryon/Meson splitting at KE T ~1 GeV, a hint of quark degrees of freedom become apparent at higher KE T. Transverse Kinetic Energy Scaling Scaling breaks Baryons scale together Mesons scale together PHENIX preliminary = m T – m PHENIX, nucl-ex/0608033 (submitted to PRL) Pressure gradients  flow  kinetic energy

37. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 37 Apparent quark number scaling works over extended range of KE T /n.  Hadron mass scaling at low KE T /n (< 1 GeV) is preserved.  Consistent with quark degrees of freedom in the initial flowing matter. Transverse Kinetic Energy Scaling PHENIX, nucl-ex/0608033 (submitted to PRL) PHENIX preliminary

38. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 38  KE T /n scaling works for the full measured range with deviation less than 10% from the universal scaling curve  Simple NCQ scaling works only at 20% level for p T >2 GeV/c, and breaks below with clear systematic dependence on the mass. PHENIX Preliminary NCQ vs. KE T /n scaling

39. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 39 KE T /n scaling observed across centralities. Centrality dep. of KE T /n scaling in Au+Au 200 GeV Arkadij Taranenko (QM06)

40. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 40 KE T /n scaling in “Cu+Cu” 200 GeV Arkadij Taranenko (QM06) KE T /n scaling also works in Cu+Cu 200 GeV.

41. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 41 v 2 vs KE T is a good way to see if v 2 for the  follows that for mesons or baryons. v 2 /n vs KE T /n scaling clearly works for  mesons as well. v 2 of  meson (Au+Au 200 GeV) Arkadij Taranenko (QM06)

42. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 42 Though the statistical errors are too large, it seems to be incompatible with the KE T /n scaling at SPS. p,  Λ  - C. Alt et al (NA49), nucl-ex/0606026. K 0 s (preliminary) - G. Stefanek (NA49), nucl-ex/0611003. KE T /n scaling of v 2 @ SPS Presented by Arkadij Taranenko (QM06)

43. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 43 Summary Onset of baryon enhancement: –p/  - ratio s indicate that an onset of baryon enhancement could be in between 22 GeV and 62 GeV. Transition from soft to hard: –High statistics, high p T PID spectra data (with detector upgrades) in Au+Au/Cu+Cu 200 GeV have been measured. –Transition from soft to hard: p T = 1.5 - 5.0 GeV/c from p/  and R cp (R AA ). –Provides further constrain to the models. Quark’s degrees of freedom: –Scaling of transverse kinetic energy with quark number (KE T /n) for v2 works well at RHIC in a wide range of centrality, for both Au+Au/Cu+Cu. –SPS v2 seems to be incompatible with KE T /n scaling. Outlook: –Run-7 (2007): Au+Au 200 GeV In PHENIX, “high p T PID upgrade project” has been completed, ready to take first physics data in Run-7. J/  v2 with new the new reaction plane detector. –PID jet correlations “Jet induced p-  p pair productions” (PHENIX, nucl-ex/0611016), still challenging for the coherent quark recombination picture. –Lower energy data scan (RHIC-II).

44. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 44 Backup Slides

45. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 45  s NN dep. of p/  + ratio (central) decreasing as a function of  s. * No weak decay feed-down correction applied.

46. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 46 R AA for protons (by ISR fit) Used ISR data at 63 GeV (Alper. NPB 100, 237) for p+p reference. Largest R AA for Cu+Cu 22.5 GeV. R AA for Au+Au 62.4 GeV is smaller than that in Cu+Cu 62.4 GeV. * No weak decay feed-down correction applied.

47. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 47 Reference data (p+p 62.4 GeV) p+p parameterization at 62.4 GeV: Fit to existing (ISR) data at similar energies (D.d'Enterria. J.Phys.G31, S491 (2005))

48. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 48 Reference data (p+p 62.4 GeV) Problem: data sets inconsistent => large error

49. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 49 Reference data (p+p 22.5 GeV) p+p parameterization at 22.4 GeV: Fit to existing data at similar energies (D.d'Enterria. J.Phys.G31, S491 (2005))

50. sQGP Mini-Workshop (2007. Feb. 16-18) @ Nagoya University, T.Chujo 50 Phenix preliminary NOTE: No weak decay feed-down correction applied. TOF (<3 GeV/c) ACC (>3 GeV/c) 0.6 - 1.5 GeV/c1.0 - 2.0 GeV/c2.0 - 3.0 GeV/c3.0 - 4.0 GeV/c 4.0 - 5.0 GeV/c Masahiro Konno (QM06)