1 / 55

Joint CATHIE/TECHQM Workshop, BNL, Dec 14-18, 2009

QGP viscosity from RHIC data. -- a hydrodynamic perspective. Huichao Song. The Ohio State University. Lawrence Berkeley National Lab. Joint CATHIE/TECHQM Workshop, BNL, Dec 14-18, 2009. Supported by DOE.

ada
Download Presentation

Joint CATHIE/TECHQM Workshop, BNL, Dec 14-18, 2009

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. QGP viscosity from RHIC data -- a hydrodynamic perspective Huichao Song The Ohio State University Lawrence Berkeley National Lab Joint CATHIE/TECHQM Workshop, BNL, Dec 14-18, 2009 Supported by DOE Thanks for collaborations and discussions from U. Heinz; Thanks for figures and discussions from K. Dusling, A. El, S. Pratt, Z. Xu,and many others 12/14/2009

  2. What is viscosity Shear viscosity – measures the resistance to flow gradients act against the buildup of flow anisotropy Bulk viscosity – measures the resistance to expansion act against the buildup of radial flow Heat conductivity – measures the ability of heat transfer Assume: (RHIC&LHC)

  3. Ideal hydrodynamics hydro S.Bass Conservation laws: ideal hydro: local equilibrium - 4 equations - 5 unknowns Input: “EOS” -EOS is one of the important factors that influence the expansion of system harder EOS (with larger ) faster expansion

  4. Viscous hydrodynamics hydro S.Bass Conservation laws: ideal hydro: local equilibrium viscous hydro: near equilibrium shear pressure tensor bulk pressure:

  5. Viscous hydrodynamics hydro S.Bass Conservation laws: - Israel-Stewart eqns.

  6. Viscous hydrodynamics hydro S.Bass Conservation laws: - Israel-Stewart eqns. viscous hydro: near-equilibrium system pre-equilibrium dynamics + viscous hydro+ hadron cascade Initial conditions final conditions

  7. Viscous hydrodynamics Input: “EOS” hydro S.Bass Conservation laws: - Israel-Stewart eqns. initial and final conditions Bjorken appro. : reduces (3+1)-d hydro to (2+1)-d hydro

  8. Qualitative effects of & on spectra The same initial & final conditions: ideal hydro viscous hydro-shear only viscous hydro-bulk only spectra Song & Heinz, 0909 -shear viscosity: flatter spectra -bulk viscosity: steeper spectra

  9. Qualitative effects of & on spectra The same initial & final conditions: ideal hydro viscous hydro-shear only viscous hydro-bulk only spectra radial flow Song & Heinz, 0909 -shear viscosity: flatter spectra; increases radial flow -bulk viscosity: steeper spectra; decreases radial flow

  10. Qualitative effects of & on V2 Elliptic flow v2 Song & Heinz, 0909 -both shear & bulk viscosity suppress V2 at low PT

  11. Shear viscosity & elliptic flow V2 Elliptic flow v2 20-25% v2 suppression -V2can be used to extract the QGP shear viscosity -For an acurrate extraction of QGP viscosity, one needs very precise V2 (experimental data & theoretical results)

  12. Shear viscosity & elliptic flow V2 Elliptic flow v2 20-25% v2 suppression -V2can be used to extract the QGP shear viscosity -For an acurrate extraction of QGP viscosity, one needs very precise V2 (experimental data & theoretical results)

  13. Shear viscosity & elliptic flow V2 Elliptic flow v2 20-25% v2 suppression Example:If v2 is increased by 10%, one need to increase by in order to describe the same exp. data -10%uncertainties in V2 translate into 50% uncertainties for the extracted value of -V2can be used to extract the QGP shear viscosity -For an acurrate extraction of QGP viscosity, one needs very precise V2 (experimental data & theoretical results)

  14. Extracting from V2 data Input / parameters for viscous hydro -initial conditions: -initial eccentricity (Glauber/CGC ; optical/fluctuations) -treatment of hadronic stage and freeze-out procedure: -EoS: EOS Q, EOS L, EOS L + chemical non-equil. HRG EOS -viscosities & relaxation times: -initialization for

  15. Effects of initial eccentricity on Glauber Luzum & Romatschke, PRC 2008 CGC -Glauber vs.CGC: ~20-30% effect on ~100% uncertainties on -event by event fluctuations: talk by A. Dumitru

  16. Effects of initial eccentricity on Glauber Luzum & Romatschke, PRC 2008 CGC NOT so fast ! -Effects fromhighly viscous & non-chemical equilibrium hadronic stage, bulk viscosity …

  17. Extracting from V2 data Input / parameters for viscous hydro -initial conditions: -initial eccentricity -treatment of hadronic stage and freeze-out procedure: -chemical composition of HRG -effects of highly viscous HRG -EoS: -viscosities & relaxation times: -initialization for shear and bulk pressure

  18. Effects of chemical composition of HRG on Partial Chemical Equilibrium (PCE) vs. Chemical Equilibrium (CE) PCE vs.CE (HRG) Ideal hydro 30% P. Huovinen 07 -PCE EoS vs. CE EoS (ideal hydro): change v2 by ~30%

  19. Effects of chemical composition of HRG on PCE vs.CE (HRG) Glauber Ideal hydro 30% 30% CGC P. Huovinen 07 Luzum &Romatschke 08 -PCE EoS vs. CE EoS (ideal hydro): change V2~30%influence ~100% -Constraining requires: a proper description of partial chemical equilibrium in HRG

  20. Effects of highly viscous hadronic stage on Ideal hydro 30-50% T. Hirano -highly viscous hadronic stage: change V2~30-50% influence ~100-150% -need viscous hydro + hadron cascade hybrid approach

  21. Extracting from V2 data Input / parameters for viscous hydro -initial conditions: -initial eccentricity -treatment of hadronic stage and freeze-out procedures: -chemical composition of HRG -viscosity of HRG -EoS: (EOSQ vs EOSL) -viscosities & relaxation times: -initialization for shear and bulk pressure

  22. Effects from softness of EOS 40% 30% Song & Heinz PRC 08 SM-EOS Q vs. EOS L --softness of EOS: ~5-10% effects on V2~25%uncertainties on -- EOS L: Katz 05 lattice data for QGP + CE EOS for HRG talk by P. Houvinen --more realistic EOS for hydro 0903 lattice data for QGP + PCE EOS for HRG

  23. Extracting from V2 data Input / parameters for viscous hydro -initial conditions: -initial eccentricity -treatment of hadronic stage and freeze-out procedures: -chemical composition of HRG -viscosity of HRG -EoS: (EOSQ vs EOSL) -viscosities & relaxation times: -initialization for shear and bulk pressure

  24. - is insensitive to initializations of and relaxation time ! shear pressure: relaxation times & initialization Song, Ph.D thesis (since is short) -when extracting : one can neglect the uncertainties from & initialization of

  25. Extracting from V2 data Input / parameters for viscous hydro -initial conditions: -initial eccentricity -treatment of hadronic stage and freeze-out procedures: -chemical composition of HRG -viscosity of HRG -EoS: (EOSQ vs EOSL) - shear pressure: relaxation times and initialization -effects from bulk viscosity

  26. bulk viscosity and relaxation time Bulk viscosity: Relaxation times: also peaks near Tc, this plays an important role for bulk viscous dynamics HRG QGP

  27. bulk viscosity and relaxation time Bulk viscosity: Relaxation times: also peaks near Tc, this plays an important role for bulk viscous dynamics HRG QGP Zero initialization: large near Tcprevents from growing to large values suppresses bulk viscous effects

  28. bulk viscosity and relaxation time Bulk viscosity: Relaxation times: also peaks near Tc, this plays an important role for bulk viscous dynamics HRG QGP N-S initialization: large near Tckeeps large negative value of in phase transition region viscous hydro breaks down ( ) for larger viscous hydro is only valid with small small bulk viscous effects on V2

  29. Uncertainties from bulk viscosity N-S initialization Zero initialization Song & Heinz, 0909 -with a critical slowing down , effects from bulk viscosity effects are much smaller than from shear viscosity bulk viscosity influences V2~5% (N-S initial.)<4% (zero initial.) uncertainties to ~20% (N-S initial.) <15% (zero initial.)

  30. Extracting from RHIC data --the current status of viscous hydrodynamics (uncertainties in V2) -initial conditions: CGC vs. Glauber~20-30% -EoS: EOS Q, vs. EOS L ~5-10% -chemical composition of HRG : (PEC vs. CE) ~30% -viscosity of HRG (or equil. HRG vs. non-equil. HRG): ~30-50% -bulk viscosity:~5%

  31. Luzum & Romatschke, PRC 2008 Glauber CGC Extracting from RHIC data --the current status of viscous hydrodynamics (uncertainties in ) -initial conditions: CGC vs. Glauber~100% -EoS: EOS Q, vs. EOS L ~25% -chemical composition of HRG : (PEC vs. CE) ~100% -viscosity of HRG (or equil. HRG vs. non-equil. HRG): ~100-150% -bulk viscosity: ~20% conservative upper limit:

  32. Luzum & Romatschke, PRC 2008 Glauber CGC Extracting from RHIC data --the current status of viscous hydrodynamics (uncertainties in ) -initial conditions: CGC vs. Glauber~100% recent progress: Heinz et al. 0907 -EoS: EOS Q, vs. EOS L ~25% -chemical composition of HRG : (PEC vs. CE) ~100% -viscosity of HRG (or equil. HRG vs. non-equil. HRG): ~100-150% -bulk viscosity: ~20% conservative upper limit: YES ! Can we further increase the accuracy of extracted?

  33. Luzum & Romatschke, PRC 2008 Glauber CGC Extracting from RHIC data --the current status of viscous hydrodynamics (uncertainties in ) -initial conditions: CGC vs. Glauber~100% recent progress: Heinz et al. 0907 -EoS: EOS Q, vs. EOS L ~25% -chemical composition of HRG : (PEC vs. CE) ~100% -viscosity of HRG (or equil. HRG vs. non-equil. HRG): ~100-150% -bulk viscosity: ~20% conservative upper limit: -To further decrease the uncertainties from bulk viscosity, (or to extract both shear & bulk viscosity from exp. data), one need more sensitive exp. observables

  34. other observables that are sensitive to - v2/ε:dependence on system size & shear viscosity -photon spectra -HBT radii … …

  35. System size dependence of shear viscous effects Song & Heinz PRC 08 -larger shear viscous suppression of elliptic flow in smaller systems

  36. System size dependence of shear viscous effects Song & Heinz PRC 08 -larger shear viscous suppression of elliptic flow in smaller systems -the slope of the multiplicity scaling ofv2/ε is sensitive to the value of shear viscosity

  37. System size dependence of shear viscous effects Song & Heinz PRC 08 -larger shear viscous suppression of elliptic flow in smaller systems -the slope of the multiplicity scaling ofv2/ε is sensitive to the value of shear viscosity

  38. System size dependence of shear viscous effects Song & Heinz PRC 08 -larger shear viscous suppression of elliptic flow in smaller systems -the slope of the multiplicity scaling ofv2/ε is sensitive to the value of shear viscosity

  39. Multiplicity scaling of v2/ε Song & Heinz PRC 08 -the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity -to reproduce the experimental data (slope), a constant is not enough!

  40. Multiplicity scaling of v2/ε Song & Heinz PRC 08 -the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity -to reproduce the experimental data (slope), a constant is not enough! -data indicate: smaller viscous effects in QGP; larger viscous effects in HRG -need viscous hydro + hadron cascade hybrid approach or inputting

  41. other observables that are sensitive to - v2/ε:dependence on system size & shear viscosity -photon spectra -HBT radii … …

  42. EM probes: Photons Photon spectra Pion spectra K. Dusling, 0903 -Viscous hardening of PT-spectra is stronger for photons than hadrons -However, earlier thermalization also leads to harder photon spectra (Dusling 0903) -Photon spectra MAY HELP to constrain the 2-d range of QGP viscosity & thermalization time, together with other observables (V2 …)

  43. other observables that are sensitive to - v2/ε:dependence on system size & shear viscosity -photon spectra -HBT radii … …

  44. HBT radii S. Pratt QM09 without viscosity with viscosity - is sensitive to the QGP viscosity - However, viscosity is only one of the many ingredients that affect HBT radii (Pratt QM09) - HBT HELPS to constrain the QGP viscosity, together with other observables (V2 …)

  45. Recent theroetical developments in viscous hydrodynamics - PT-dependent of viscous modification of the particle distributions Talk by D.Teaney and D. Molnar - in multi-component systems Talk by G. Denicol - 3rd order viscous hydrodynamics Talk by A. El - 3+1-d viscous hydro: Several groups are working on it (MSU, Frankfurt, Krakow, etc)

  46. A short summary - is sensitive to A first attempt to constrain from RHIC data indicates BUT: to extract QGP viscosity, one must consider (at least) all the following aspects: - a realistic EOS: EOS L vs. SM-EOS Q, PCE vs. CE - initial conditions: CGC vs. Glauber initialization, optical vs. fluctuations - bulk viscosity: uncertainties from bulk viscosity - hadronic stage : viscous hydro+ hadron cascade … … … …

  47. Thank You

  48. EOS EOS

  49. Qualitative effects of & on V2 ideal hydro Elliptical flow v2 Song & Heinz, 0909 viscous hydro (shear only) Change the flow profile during hydro evolution Flow + spectra correc. Spectra correc.: viscous hydro (bulk only) (with only flow correction here) A. Monnai talk : spectra correc. for bulk viscosity -v2 is sensitive to viscosity, especially shear viscosity

  50. EM probes: Photons Photon spectra Photon spectra K. Dusling, 0903 -Photon spectra are more sensitive to QGP shear viscosity than hadrons -Photon spectra are also sensitive to hydro starting time -Photon spectra mayHELP to constrain QGPshear viscosity andhydro starting time • More sophisticated theoretical modeling in the future: including photon emitted from hadronic stage with modified photon emission rate, etc ; better experimental data

More Related