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Quark number susceptibility with finite chemical potential in hQCD. Youngman Kim. with Y. Matsuo, W. Sim, S. Takeuchi, T. Tsukioka, arXiv:1001.5343[hep-th] (Harish-Chandra Research Institute, Samsung, APCTP). Plan. Why qSUS? Holographic QCD in a nutshell
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Quark number susceptibility with finite chemical potential in hQCD Youngman Kim with Y. Matsuo, W. Sim, S. Takeuchi, T. Tsukioka, arXiv:1001.5343[hep-th] (Harish-Chandra Research Institute, Samsung, APCTP)
Plan • Why qSUS? • Holographic QCD in a nutshell • qSUS with finite chemical potential • Discussion
Signal of CEP (two flavor QCD) Allton et al, Phys.Rev.D71:054508,2005
hQCD in a nutshell AdS/QCD ?
A review: J. Erdmenger, N. Evans, I. Kirsch, E. Threlfall, Eur.Phys.J. A35:81-133,2008.
AdS/CFT Dictionary 4D CFT (QCD) 5D AdS 4D generating functional 5D (classical) effective action Operator 5D bulk field [Operator] 5D mass Current conservation gauge symmetry Large Q small z Confinement Compactified z Resonances Kaluza-Klein states
Example: holographic deconfinement transition E. Witten, Adv. Theor. Math. Phys. 2, 505 (1998), C. P. Herzog, Phys. Rev. Lett.98, 091601 (2007) 1. thermal AdS: 2. AdS black hole: (De)confinement transition Transition between two backgrounds
Example: retarded Green’s function in hQCD Solving the EoM of the bulk field with in-falling boundary condition
From the first and second equations, In-falling BC Now we are to solve the EoM for F(u) in the limit of long-wave length and low-frequency.
Following the procedure, we obtain the retarded Greens function diffusion constant D. T. Son, and O. Starinets, JHEP09 (2002) 042; G. Policastro, D. T. Son, and O. Starinets, JHEP09 (2002) 043
An AdS BH with U(1) charge U(1) gauge symmetry in bulk U(1) global symmetry in gauge theory side
(negative specific heat) Chemical potential “The conformal field theory is in a thermal ensemble for which a certain U(1) charge density has also been turned on.’’ A. Chamblin, R. Emparan, C. V. Johnson, and R. C. Myers, PRD (1999)
Certainly, the transition is first order due to large Nc nature of the present approach. • For small chemical potential, there is a possibility to connect low and high T smoothly with 1/Nc corrections. • For large chemical potential, there is no hope. • So, with 1/Nc corrections, the transition is like crossover for small chemical potential and first order for large chemical potential. But it is only speculation.
Discussion • Finite quark mass effect? (in progress) • RN-AdS is describing QGP-like system with finite chemical potential. • What is the gravity background dual to QGP with/without density? • Generic problem is of course to collect all 1/Nc corrections in a consistent way.