### Abstract

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 H
_{2}
O, 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].

Original language | English |
---|---|

Pages (from-to) | 18-21 |

Number of pages | 4 |

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

Volume | 670 |

Issue number | 1 |

DOIs | |

Publication status | Published - 2008 Dec 4 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Nuclear and High Energy Physics

### Cite this

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

*670*(1), 18-21. https://doi.org/10.1016/j.physletb.2008.10.024

**Phase transitions and perfectness of fluids in weakly coupled real scalar field theories.** / Chen, Jiunn Wei; Huang, Mei; Li, Yen Han; Nakano, Eiji; Yang, Di-Lun.

Research output: Contribution to journal › Article

*Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics*, vol. 670, no. 1, pp. 18-21. https://doi.org/10.1016/j.physletb.2008.10.024

}

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

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 H 2 O, 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 H 2 O, 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].

UR - http://www.scopus.com/inward/record.url?scp=55749099966&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=55749099966&partnerID=8YFLogxK

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 -