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Viscosity at RHIC

Viscosity at RHIC. Scott Pratt & Kerstin Paech Michigan State University. OUTLINE. What is viscosity? Sources of viscosity Bulk viscosity near T c. Definition of Viscosity. After boosting and rotating,. P, B and  are functions of . Definition of Viscosity.

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Viscosity at RHIC

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  1. Viscosity at RHIC Scott Pratt & Kerstin Paech Michigan State University Scott Pratt Michigan State University

  2. OUTLINE • What is viscosity? • Sources of viscosity • Bulk viscosity near Tc Scott Pratt Michigan State University

  3. Definition of Viscosity After boosting and rotating, P, B and  are functions of  Scott Pratt Michigan State University

  4. Definition of Viscosity Viscosity = change in "pressure" to due expansion Bulk viscosity = change due to isotropic expansion Shear viscosity = change due to anisotropic expansion Scott Pratt Michigan State University

  5. Sources of Viscosity 1. If ∂zvz >∂xvx , Vanishes if mean free path -> 0 Scott Pratt Michigan State University

  6. Sources of Viscosity 2. If Rinteraction > 0 , Important at early times Scott Pratt Michigan State University

  7. v2 from Boltzmann Calculation Finite-range effects dampen v2 S. Cheng, S. P., P. Csizmadia, Y. Nara, D. Molnar, M. Gyulassy, S.E. Vance & B. Zhang, PRC 65, 024901 (2002) Scott Pratt Michigan State University

  8. Sources of Viscosity 3. Longitudinal Fields Hyper-shear at very early times Increases transverse acceleration Scott Pratt Michigan State University

  9. Sources of Viscosity 4. Longitudinal Fields, Hyper-shear for < 0.5 fm/c Increases transverse acceleration Scott Pratt Michigan State University

  10. Sources of Viscosity 5. Chemical non-equilibrium offset fromequilibrium Using some thermodynamics Large when T falls or when m rises Scott Pratt Michigan State University

  11.  can blow up at phase transition! Sources of Viscosity 6. Mean fields Langevin "force" Scott Pratt Michigan State University

  12. K.Paech & A.Dumitru, PLB 623, 200 (2005) Example: Linear Sigma Model 1st order when g>3.55 Scott Pratt Michigan State University

  13. Example: Linear Sigma Model 1st order when g > 3.5549 Scott Pratt Michigan State University

  14. Example: Linear Sigma Model For g=3.4, Txx -> 0 Scott Pratt Michigan State University

  15. P Txx r How might this affect dynamics? • "traffic jam" • flash-like emission Scott Pratt Michigan State University

  16. Random Lessons • Numerous sources of viscosity • Finite collision time (shear) • Finite interaction range (shear & bulk) • Longitudinal fields (shear) • Chemical non-equilibrium (bulk) • Non-equilibrium fields (bulk) • Shear viscosity important at early times • Affects elliptic flow • Bulk viscosity important near Tc • Affects dynamics ?? • Alternatively, effects can be included through • Explicit chemical evolution • Explicit evolution of fields K.Paech & A.Dumitru, PLB 623, 200 (2005) Scott Pratt Michigan State University

  17. Support your local theorist!! http://www.phy.duke.edu/~muller/RTI_Complete.pdf Scott Pratt Michigan State University

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