New Results from Viscous Hydro + URQMD (VISHNU)

CPOD 2011, Wuhan, Nov 7-11, 2011

References:

Supported by DOE

05/04/2011

QGP viscosity at RHIC and LHC energies

H. Song , S. Bass and U. Heinz, Phys. Rev. C83, 024912 (2011)H. Song, S. Bass, U. Heinz, T. Hirano and C. Shen, Phys. Rev. Lett. 106, 192301(2011) H. Song, S. Bass, U. Heinz, T. Hirano and C. Shen, Phys. Rev. C83, 054910(2011)

1H. Song, S. Bass, U. Heinz, Phys Rev. C83 054912(2011)

Huichao Song 宋慧超

0)( xT gpuupeT )()(

u

TT

212

u

TT

u21)(

viscous hydrodynamics

)( p Input: “EOS”

2

Viscous hydro: Shear viscosity & elliptic flow V2

20-25% v2 suppression

41

s

Elliptic flow v2

-V2 can be used to extract the QGP shear viscosity

-For an accurate extraction of QGP viscosity, one needs to control the theoretical uncertainties as well as precise exp data.

H. Song and U. Heinz, PRC08

3

(GeV)Tp0 1

~30%

Partially Chemical equil.

Ideal hydro

P. Huovinen 07

Hadronic effects on elliptic flow V2 hadronic dissipative effects

~30-50%

-These two HRG effects are not included in early viscous hydro calculations

T. Hirano 06

viscous hydro + hadron cascade (URQMD) hybrid approach

URQMD includes the partially chemical equilibrium nature & hadronic dissipative effects

4

STAR DATA

~20% uncertainties in EXP V2 ~100% uncertainties for the extracted QGP viscosity

V2 from different exp methods are affected by non-flow and fluctuations

~20%

Extracting QGP viscosity from RHIC data

EXP.

5

Ollitrault, Poskanzer & Voloshin, PRC09Corrected v2:

with assumptions on fluctuations and non flow, all corrected v2 in participant / reaction plan converge to unique curves

greatly reduces uncertainties from EXP data for the extracted s/

Corrected V2

Extracting QGP viscosity from RHIC data

EXP.

6

-initial conditions-EoS: s95p-PCE Huovinen & Petreczky10

-chemical composition of HRG -viscosity of HRG-bulk viscosity: <20%

Viscous Hydro + URQMD

Extracting QGP viscosity from RHIC data

Song & Heinz, PRC 09

Theoretical Modeling

7

Song, Bass & Heinz, PRC2011

-initial conditions

QGP viscosity from dydNSv /)/1(/2

24.016.0/ s for MC-KLN initial conditions

for MC-Glauber initial conditions 16.008.0/ s

MC-KLN MC-Glauber(Part. Plan) (Part. Plan)

8H. Song, S. Bass, U. Heinz, T. Hirano, and C. Shen, PRL2011

-a nice fit for both pion and proton spectra, insensitive to QGP viscosity

H. Song, S. Bass, U. Heinz, T. Hirano, and C. Shen, PRC2011

9

24.016.0/ s for KLN initial condi.for Glauber initial condi.16.008.0/ s

-hit the lower-bound of extracted from (non flow effects) dydNSv /)/1(/2 s/ -fluctuating effects is reduced by comparing theory & EXP. /2v

22 /}2{ v

5-10%20-30%

30-40%

40-50%

5-10%20-30%

30-40%

40-50%

20-30%

30-40%

40-50%

20-30%

30-40%

40-50%

08.0/ s

16.0/ s

Glauber Glauber

KLN KLN

H.Song, S. Bass , U. Heinz, T. Hirano, and C. Shen, PRC2011

10

QGP viscosity at RHIC & LHC energies

11

-- H. Song, S. Bass, U. Heinz, PRC2011

V2(PT) at RHIC and LHC

Assuming const. s/

This is not aim for extracting QGP viscosity at LHC energy with reliable uncertainty estimates

16.0/ s24.020.0/ s

RHIC:LHC:

12

Song, Bass & Heinz, PRC 2011

V2(PT) for pion kaon & protons at LHC

Assuming const. s/

This is not aim for extracting QGP viscosity at LHC energy with reliable uncertainty estimates

20.0/ sLHC:

13

A short summary- is sensitive to

Extraction from elliptic flow data using viscous hydro + UrQMD indicates:

)41(3/)41(1 ss/

s/2v

)4/1()21(/ s

-Relatively smaller uncertainties are from

-other possible observables may help to reduce these uncertainties ,

initial flow, bulk viscosity, single short hydro vs. e-by-e simulations …

photons, HBT radii, triangular flow …

-Relatively larger uncertainties are from initial geometry MC-Glauber: MC-KLN: )4/1()32(/ s

14

Similar averaged QGP viscosity at RHIC and LHC energies

15

Thank You

e-b-e hydro vs. single shot hydro

Event-by-event hydro produces

5% less v2/ecc than single-

shot hydro with smooth

averaged initial profile

Zhi & Heinz, preliminary results

16

24.016.0/ s for MC-KLN initial conditions

for MC-Glauber initial conditions 16.008.0/ s

initial flow, bulk viscosity and e-b-e hydro:cancelation among them

each of them shifts v2 by a few percent

17