TY - JOUR

T1 - Phase transitions and perfectness of fluids in weakly coupled real scalar field theories

AU - Chen, Jiunn Wei

AU - Huang, Mei

AU - Li, Yen Han

AU - Nakano, Eiji

AU - Yang, Di Lun

N1 - Funding Information:
We thank Tom Cohen, Yusuke Nishida, Dirk Rischke, Dam Son and Larry Yaffe for useful discussions. M.H. thanks the National Taiwan University for hospitality. J.W.C. thanks the University of Washington for hospitality. This work is supported by the IHEP, Chinese Academy of Sciences, CAS key project KJCX3-SYW-N2, NSFC10735040, and the NSC and NCTS of Taiwan.

PY - 2008/12/4

Y1 - 2008/12/4

N2 - We calculate the ratio η / s, the shear viscosity (η) to entropy density (s), which characterizes how perfect a fluid is, in weakly coupled real scalar field theories with different types of phase transitions. The mean-field results of the η / s behaviors agree with the empirical observations in atomic and molecular systems such as H2O, He, N, and all the matters with data available in the NIST database. These behaviors are expected to be the same in N component scalar theories with an O (N) symmetry. We speculate these η / s behaviors are general properties of fluid shared by QCD and cold atoms. Finally, we clarify some issues regarding counterexamples of the conjectured universal bound η / s ≥ 1 / 4 π found in Refs. [T.D. Cohen, Phys. Rev. Lett. 99 (2007) 021602, hep-th/0702136; A. Cherman, T.D. Cohen, P.M. Hohler, arXiv: 0708.4201 [hep-th]; A. Dobado, F.J. Llanes-Estrada, Eur. Phys. J. C 51 (2007) 913, hep-th/0703132].

AB - We calculate the ratio η / s, the shear viscosity (η) to entropy density (s), which characterizes how perfect a fluid is, in weakly coupled real scalar field theories with different types of phase transitions. The mean-field results of the η / s behaviors agree with the empirical observations in atomic and molecular systems such as H2O, He, N, and all the matters with data available in the NIST database. These behaviors are expected to be the same in N component scalar theories with an O (N) symmetry. We speculate these η / s behaviors are general properties of fluid shared by QCD and cold atoms. Finally, we clarify some issues regarding counterexamples of the conjectured universal bound η / s ≥ 1 / 4 π found in Refs. [T.D. Cohen, Phys. Rev. Lett. 99 (2007) 021602, hep-th/0702136; A. Cherman, T.D. Cohen, P.M. Hohler, arXiv: 0708.4201 [hep-th]; A. Dobado, F.J. Llanes-Estrada, Eur. Phys. J. C 51 (2007) 913, hep-th/0703132].

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U2 - 10.1016/j.physletb.2008.10.024

DO - 10.1016/j.physletb.2008.10.024

M3 - Article

AN - SCOPUS:55749099966

VL - 670

SP - 18

EP - 21

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

SN - 0370-2693

IS - 1

ER -