1 / 15

Perfect liquid at RHIC! Problem: all fluids have viscosity.

with Abdel-Aziz in progress. How Can We Measure Viscosity? Sean Gavin Wayne State University. Perfect liquid at RHIC! Problem: all fluids have viscosity. Fundamental question: how big is the viscosity?.

jamese
Download Presentation

Perfect liquid at RHIC! Problem: all fluids have viscosity.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. with Abdel-Aziz in progress How Can We Measure Viscosity?Sean Gavin Wayne State University Perfect liquid at RHIC! Problem: all fluids have viscosity. Fundamental question: how big is the viscosity? I. Viscosity and its consequences II. Radial flow fluctuations: Dissipated by shear viscosity III. Contribution to transverse momentum fluctuations

  2. Viscosity viscous contribution to stress tensor, flow velocity v << 1 shear viscosity  resists shear flow vx(z) bulk viscosity  resists expansion “hubble” flow important: typically  << 

  3. How Good is the Perfect Fluid? How can we measure viscosity of parton and hadron fluids? • measure flow through a fixed geometry  elliptic and radial flow; cooling Muronga et al.; Teaney et al.; Heinz, Song & Chaudhuri • fluid response to external probe  jet phenomena, Mach cone Casalderry-Solana, Shuryak & Teaney • attenuation of sound waves  propose:dissipation of fluctuations

  4. Radial Flow Fluctuations average radial flow  vr  small fluctuations u ≈ vr  vr  shear viscosity drives velocity toward the average friction between neighboring radial sheets ask: how can measured fluctuations  viscosity?

  5. z Evolution of Fluctuations u r momentum current: u(z,t) ≈ vr  vr  4-momentum conservation diffusion of small fluctuations + corrections O(R-1) momentum diffusion length shear viscosity  energy density e, pressure P

  6. Viscosity Broadens Rapidity Distribution analogous effect in charge diffusion Stephanov & Shuryak; Abdel-Aziz & Gavin; Koide; Sasaki et al.; Wolchin; Teaney & Moore; Bass, Pratt & Danielowicz viscous diffusion + Bjorken flow random walk in rapidityyvs. proper time V = 2s/0 V momentum diffusion lengths (e+P) formation at0 /0

  7. fluctuations equilibrate by diffusing through volume global equilibrium – diffusion drivesr   Hydrodynamic Momentum Correlations momentum density correlation function equilibrium difference rg rg r g,eqsatisfies diffusion equation Van Kampen, Stochastic Processes in Physics and Chemistry, (Elsevier, 1997); Gardiner, Handbook of Stochastic Methods, (Springer, 2002) width in relative rapidity grows from initial value :

  8. Dynamic Fluctuations Pruneau, Voloshin & S.G. variance minus thermal contribution multiplicityN meanpt correlation function:

  9. ptFluctuations Energy Independent

  10. Hydrodynamic Momentum Correlations pt fluctuations probetransverse momentum density density correlations momentum density correlations observable: measured pt1pt2 plus HIJING R rg and rn are comparable

  11. Abdel-Aziz, S.G - in progress How Much Viscosity? sticky sQGP core + hadronic corona see Hirano & Gyulassy two extreme scenarios: V perfect sticky liquid pQGP ~HRG~ 2 fm perfect liquid sQGP ~ (4 Tc)-1,HRG~ 2 fm  (fm) fluctuations, rapidity window: • Gaussian rg, width  • initial~ 0.25 balance function initial perfect sticky 

  12. Summary multiple scattering phenomena broadens width of rapidity distribution testing the perfect liquid  viscosity info • diffusion coefficient shear viscosity • compare rapidity width of momentum fluctuations for different projectile sizes and energies • cross-check: combine with other indirect viscosity measures schematic calculation -- lots to do: • Maxwell/Muronga type corrections • O(R-1) corrections • angular correlations

  13. Hydrodynamic Density Correlations hydro: stress-energy tensor T and current j number density n = j0 and momentum density gi = T0i phase space density f(x,p)fluctuates: multiplicity fluctuations probedensity density correlation function Measured: NA49; PHENIX; PHOBOS

  14. Hydrodynamic Momentum Correlations pt fluctuations probetransverse momentum density momentum density correlation function observable: measured pt1pt2 plus HIJING R rg and rn are comparable

  15. How Good is the Perfect Fluid? shear viscosity  resists shear flow How can we measure viscosity? • measure flow through a fixed geometry  elliptic and radial flow; cooling Muronga et al.; Teaney et al.; Heinz, Song & Chaudhuri • fluid response to external probe  jet phenomena, Mach cone Casalderry-Solana, Shuryak & Teaney • attenuation of sound waves  propose:dissipation of fluctuations vx(z)

More Related