Hadron production by quark combination in Pb+Pb collisions at SPS

1. Hadron production by quark combination in Pb+Pb collisions at SPS C.E.Shao, J.Song, F.L.shao, Q.B.Xie, Phys. Rev. C 80, 014909 (2009) 邵凤兰曲阜师范大学 十三届中高能核物理会议 安徽合肥，11.5-11.7，2009 1

2. Outline • Introduction • Quark combination rule and symmetry • Results and discussions • Summary 2

3. hadronic phase and freeze-out QGP and hydrodynamic expansion initial state pre-equilibrium hadronization Introduction Exploring QGP Matter at RHIC Studying hadronization mechanism

4. (1) high jets approaches (2) thermal photons (3) Thermal hadrons

5. some experimental phenomena at RHIC: PRL97,152301(2006), STAR

6. PRL98,162301(2007), STAR KET =mT -m Perfect scaling for all measured hadrons Difference in baryon and meson v2.

7. R. Hwa, C. B. Yang (recombination) • R. J. Fries, et al., (recombination) • C. Ko, L. W. Chen, et al. (Coalescence) • Q. B. Xie, F. L. Shao (SDQCM)

8. 17.3 GeV ≈3 Some experimental evidences at SPS • Energy density （top SPS---158AGeV） 2. quark number scaling of V2

9. 3. Onset of deconfinement at lower SPS （30 AGeV）

10. Quark combination rule and symmetry near correlation in phase space

12. W.Han, S.Y.Li, Y.H.Shang, F.L.Shao, T.Yao, Phys. Rev. C 80, 035202 (2009) F.L.Shao, Q.B.Xie, Q.Wang, Phys. Rev. C 71, 044903 (2005) T.Yao,W.Zhou, Q.B.Xie, Phys. Rev. C 78, 064911 (2008)

13. Results and discussions

14. yields

15. Rapidity distribution

17. spectra pT

18. B/M ratio

19. Central Au+Au collisions at 200 GeV

20. Exploring QGP matter properties

23. Collective flow u,d s The collective flow of strange quarks is stronger than that of light quarks; this result is similar to that obtained at RHIC.

24. strangeness The strangeness is almost the same.

25. Summary ●The combination mechanism can describe the hadron production at RHIC and SPS energies. ●The collective flow of strange quark is stronger than that for light quarks; The strangeness is almost the same from SPS to RHIC energies. Thank you !

26. Issues faced by the combination mechanism： Entropy and energy conservation

27. Quark combination rule and SU_f(3 )symmetry If theyare close to each other in phase space, they can interact withsufficient time to be in the color singlet and form a meson. baryon. If the neighbor is a q, because the attraction strengthof the singlet is two times that of the antitriplet, then qq willwin the competition to form a meson and leave a q alone tocombine with other quarks or antiquarks.

28. quark combination mechanism • V. V. Anisovich, et al.,(1973) • J. D. Bjorken, et al., (1974) • K.P. Das & R.C. Hwa (1977) • Q. B. Xie, et al. (1980’s) • in RHIC, for “QGP” hadronization • R. Hwa, C. B. Yang, et al., (recombination) • R. J. Fries et al., (recombination) • C. Ko, L. W. Chen, et al. (Coalescence) • Q. B. Xie, F. L. Shao (SDQCM)

29. Quark combination model Combination rule： Near correlation in rapidity Momentum distributions of quarks The smaller the difference in rapidity for two(three) quarks, the longer is the interaction time. So there is enough time for a to be in a color singlet and form a meson(baryon). decay final hadron

31. 4）QCM 面临的普适性挑战 • RHIC 能量不同快度、不同pT,尤其是大、小 pT下的强子谱 • 扩展到不同能量 ( LHC )，不同中心度 • 回过头来到 ( RHIC,Tevtron,LHC ), e+- e- • 最重要的一个挑战是用到宇宙学。RHIC 和 LHC 研究 • QGP 本来就是为了了解宇宙初期的物质状态 ，它的 • 强子化应该体现为宇宙演化的结果。 强子化机制的普适性是粒子物理、核物理、 宇宙学的连接点和切入点。

32. backup slides ---1 The average constituent quark number : where λsisthe strangeness suppression factor

33. backup slides ---2 Stationary thermal source Integrating over rapidity

34. backup slides ---3 Integrating over the transverse components nonuniform longitudinal flow where w(y) isphenomenological expansion function

35. backup slides ---6 perturbative QCD calculation :

36. PHENIX Data-Sets 30 times 3 times Collided 4 different species in 8 years: AuAu, dAu, pp, CuCu 6 energies run: 9.2 GeV, 19 GeV, 22.5 GeV, 62.4 GeV, 130 GeV, 200 GeV