Application of AdS/CFT in high energy nuclear physics Hefei, Nov 5th, 2009 黄 梅黄 梅 中国科学院高能物理研究所 中国科学院大科学装置 理论物理中心

2 Content I.AdS/CFT & sQGP Shear viscosity over entropy density Equation of state Bulk viscosity over entropy density II. AdS/CFT & hadron physics Hard wall AdS 5 model Soft-wall AdS 5 model Dp-Dq model

3 The birth of string theory in 1960’s was to understand strong interaction. It’s the time for string theory coming back to finish its original task !?

4 AdS/CFT Maldacena (1997)

5 QCDQCD ? String theory, quantum gravity Non-Abelian gauge theory AdS/CFT conjecture If it’s true for any gauge theory Then what ’ s the dual string theory of QCD?

6 Metric structure of holographic QCD (5D) QCD Dp-Dq system in type-II superstring theory (10D) First step, is it possible to find a 5D holographic model of QCD?

7 I. AdS/CFT & sQGP Shear viscosity over entropy density Equation of state Bulk viscosity over entropy density what I didn’t cover in this talk: energy loss, (H.Liu et.al., Y.Gao et.al. and many others) heavy quark dissociation (Hou, Ren and many others) ……

8 Discovery of sQGP at RHIC Low shear viscosity Shear viscosity over entropy density

9 Increase shear viscosity reduces elliptic flow! P. Romatschke, U. Romatschke, nucl-th/ Before 2003, people believed that de-confined QCD matter would be weakly coupled gas, pQCD gives: See Qun Wang’s talk

10 Handling strongly coupled system by using AdS/CFT Minimum bound?

11 Universality of  /s=1/4  ? Violation of the minimum bound in higher derivative gravity / dilaton coupling M. Brigante, H. Liu, R.C. Myers, S. Shenker, S. Yaido , R.G. Cai, Z.Y. Nie, N. Ohta, Y.W. Sun, S.Pu, Q. Wang,

12 sQGP: Most “perfect fluid” known Lattice: Nakamura-Sakai(2004) Meyer (2007) Water Policastro, Son, and Starinets; Kovton, Son and Starinets; Buchel, J. Liu; Maeda, Natsuume, Okamura N =4 SYM : RHIC: Teaney (2003) Romatschke-Romatschke (2007)

13 However, QCD is not a conformal theory Trace anomaly Nonzero bulk viscosity AdS/CFT QCD

14 LQCD results: trace anomaly shows a sharp peak near phase transition BNL-Columbia-RBRC-Bielefeld, arXiv: Bielefeld, hep-lat/ Non-conformality: EOS and bulk viscosity over entropy density

15 BNL-Columbia-RBRC-Bielefeld arXiv: LQCD results: soft EOS & small sound velocity near phase transition

16 Dmitri Kharzeev, Kirill Tuchin arXiv: [hep-ph], F.Karsch, Dmitri Kharzeev, Kirill Tuchin arXiv: [hep-ph], Harvey Meyer arXiv: [hep-ph], Nonzero bulk viscosity of QCD matter near phase transition Pure gluodynamics 2-flavor case

17 Gubser et al, D Gravity couples to a dilaton, nonconformal

18 J.W Chen, MH, Y.H. Li, E. Nakano, D.L.Yang arXiv: Baochun Li, Mei Huang, arXiv: Scalar theory: Minimum at Tc for shear viscosity over entropy density Maximum at Tc for bulk viscosity over entropy density Dual theory: Minimum at Tc for shear viscosity over entropy density (no result) Maximum at Tc for bulk viscosity over entropy density (yes)

19 J. Noronha,

20 II.AdS/CFT & Hadron Physics hard-wall AdS5 model soft-wall AdS5 model Dp-Dq model

Can AdS 5 metric describe hadron spectra? hard-wall AdS 5 model

Lowest excitations: 10-20% agreement

However, no Regge behavior in the hard-wall AdS 5 model !

How to improve AdS 5 metric? Introduce a dilaton field to restore Regge behavior soft-wall AdS 5 model or KKSS model

25 No Regge behavior for axial meson in soft-wall AdS 5 model S. He, M. Huang, Q. S. Yan, Y. Yang,

26 Dp-Dq model S. He, M. Huang, Q. S. Yan, Y. Yang,

27

28 19 scalars below 2GeV Below 1 GeV, tetraquark nonet (inverse mass odering) Above 1GeV, quark antiquark nonet + one glueball

29 Operator and 5D mass

30 Spectra in Dp-Dq model: D4 background is more favored C. Wang, S. He, M. Huang, Q. S. Yan, Y. Yang,

1.It seems possible to describe QCD properties using holographic method, 2.Still need a lot of efforts to find the right holographic QCD model. In summary Welcome to KITPC program “AdS/CFT and Novel Approaches to Hadron and Heavy Ion Physics” From to , KITPC

33 Relativistic Heavy Ion Collision Discovery of “Perfect fluid” at RHIC Hydrodynamics ???

34 A little bit Hydrodynamics

35 x Non-central Collisions beam y x pypy pxpx Elliptic Flow v2