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Phase Transitions and the Perfectness of Fluids. Jiunn-Wei Chen National Taiwan U. Review: shear viscosity, and the minimum bound conjecture QCD shear viscosity in the hadronic phase: (a) zero density (b) nuclear L-G phase transition Scalar field theory.
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Phase Transitions and the Perfectness of Fluids Jiunn-Wei Chen National Taiwan U.
Review: shear viscosity, and the minimum bound conjecture • QCD shear viscosity in the hadronic phase: (a) zero density (b) nuclear L-G phase transition • Scalar field theory
Shear viscosity Frictional force
Shear viscosity measures how “perfect” a fluid is!
Kovtun, Son, and Starinets (’05) Conjecture: Shear viscosity / entropy density • Motivated by AdS/CFT
QGP (quark gluon plasma) almost saturates the bound @ just above Tc --- a perfect fluid (Teaney; Romatschke, Romatschke; Song, Heinz) • LQCD, gluon pasma (Karsch, Wyld; Nakamura, Sakai; Meyer) • What happens below Tc?
Pion gas ChPT (chiral perturbation theory) • Non-perturbative in coupling Boltzman equation
The Landscape JWC, Li, Liu, Nakano
Cold Unitary Atoms Rupak & Schafer 2007 Lacey et al., PRL 98:092301,2007
of Water (Lacey et al.)
(JWC, M. Huang, Y.H. Li, E. Nakana, D.L. Yang) 1st-order phase transition a > 0, b < 0, c > 0 2nd-order p.t.: a < 0, b > 0, c = 0 crossover: + No p.t.: a > 0, b > 0, c = 0
Boltzmann? • CJT formulism (Cornwall, Jackiw, Tomboulis) • Mean field calculation
f Just one minimum (a < 0)? O(N) model? Large b?
Invading the bound (I) w/o flavor changing (KSS; Cohen; Cherman, Cohen, Hohler)
Invading the bound (II) (T. Cohen)
Invading the bound (III) Higher derivative gravity (Brigante, Liu, Myers, Shenker, Yaida; Kats, Petrov): O(1/N) effect could invade the bound. Could the bound be saved by some consistency requirement (e.g. stability)?
QCD Bulk Viscosity Karsch, Kharzeev, Tuchin; Meyer; JWC, Wang
Outlook • Universal and behaviors? ( reaches local minimum near p.t. reaches local maximum near p.t.) • Mapping QCD phase diagram by Locating critical end point (Lacey)
QCD Phase Diagram Probing critical end point by (Lacey)
Outlook just below Tc for YM
Question • Which shear viscosity is bigger? Liquid or gas water near 100 degree C at 1 atm?