Joint CATHIE/TECHQM Workshop, BNL, Dec 14- 18, 2009 Huichao Song The Ohio State University Supported by DOE 12/14/2 009 Lawrence Berkeley National Lab QGP viscosity from RHIC data -- a hydrodynamic perspective 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
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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. - PowerPoint PPT Presentation
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Joint CATHIE/TECHQM Workshop, BNL, Dec 14-18, 2009
Huichao Song
The Ohio State University
Supported by DOE
12/14/2009
Lawrence Berkeley National Lab
QGP viscosity from RHIC data -- a hydrodynamic perspective
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
What is viscosity Shear viscosity – measures the resistance to flow gradients
Bulk viscosity – measures the resistance to expansion
Heat conductivity – measures the ability of heat transfer
Assume: (RHIC&LHC)0,0 n
act against the buildup of flow anisotropy
act against the buildup of radial flow
Ideal hydrodynamics
0)( xT
S.Bass
Conservation laws: pguupeT )(
ideal hydro: local equilibrium
)( p Input: “EOS” epcs /2
- 4 equations
- 5 unknowns ,e )3(u,p
-EOS is one of the important factors that influence the expansion of system harder EOS (with larger )2
s/uncertainties to ~20% (N-S initial.) <15% (zero initial.)
fm/c120)/( s
s/ s/
Extracting from RHIC data --the current status of viscous hydrodynamics
s/
-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%
(uncertainties in V2 )
Extracting from RHIC data --the current status of viscous hydrodynamics
s/
Glauber CGC
Luzum & Romatschke, PRC 2008
-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%
(uncertainties in )s/
conservative upper limit:
)41(5/ s
Extracting from RHIC data --the current status of viscous hydrodynamics
s/
Glauber CGC
Luzum & Romatschke, PRC 2008
-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%
(uncertainties in )s/
conservative upper limit:
)41(5/ s
Can we further increase the accuracy of extracted ? YES !s/
recent progress: Heinz et al. 0907
Extracting from RHIC data --the current status of viscous hydrodynamics
s/
Glauber CGC
Luzum & Romatschke, PRC 2008
-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%
(uncertainties in )s/
conservative upper limit:
)41(5/ s
recent progress: Heinz et al. 0907
-To further decrease the uncertainties from bulk viscosity, (or to extract both shear & bulk viscosity from exp. data), one need more sensitive exp. observables
other observables that are sensitive to s/
- v2/ε: dependence on system size & shear viscosity
-photon spectra
-HBT radii
… …
Song & Heinz PRC 08
-larger shear viscous suppression of elliptic flow in smaller systems
System size dependence of shear viscous effects/v2
Song & Heinz PRC 08
System size dependence of shear viscous effects/v2
-the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity
-larger shear viscous suppression of elliptic flow in smaller systems
Song & Heinz PRC 08
System size dependence of shear viscous effects/v2
-larger shear viscous suppression of elliptic flow in smaller systems
-the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity
Song & Heinz PRC 08
System size dependence of shear viscous effects/v2
-larger shear viscous suppression of elliptic flow in smaller systems
-the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity
Multiplicity scaling of v2/ε Song & Heinz PRC 08
-to reproduce the experimental data (slope), a constant is not enough!
-the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity
s/
Multiplicity scaling of v2/ε Song & Heinz PRC 08
-to reproduce the experimental data (slope), a constant is not enough!
-the slope of the multiplicity scaling of v2/ε is sensitive to the value of shear viscosity
-data indicate: smaller viscous effects in QGP; larger viscous effects in HRG
- v2/ε: dependence on system size & shear viscosity
EM probes: Photons Pion spectra
-Viscous hardening of PT-spectra is stronger for photons than hadrons
K. Dusling, 0903
20 ~/T
pp
peff
Photon spectra
1
~sTpe
-Photon spectra MAY HELP to constrain the 2-d range of QGP viscosity & thermalization time, together with other observables (V2 …)
-However, earlier thermalization also leads to harder photon spectra (Dusling 0903)
other observables that are sensitive to s/
-photon spectra
-HBT radii
… …
- v2/ε: dependence on system size & shear viscosity
HBT radii
sideout RR /- is sensitive to the QGP viscosity
- HBT HELPS to constrain the QGP viscosity, together with other observables (V2 …)
S. Pratt QM09
with viscosity
without viscosity
- However, viscosity is only one of the many ingredients that affect HBT radii (Pratt QM09)
Recent theroetical developments in viscous hydrodynamics
(MSU, Frankfurt, Krakow, etc)
- 3+1-d viscous hydro: Several groups are working on it
- in multi-component systems
- 3rd order viscous hydrodynamics
f
Talk by A. El
Talk by G. Denicol
Talk by D.Teaney and D. Molnar
- PT-dependent of viscous modification of thefparticle distributions
A short summary
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
- is sensitive to
A first attempt to constrain from RHIC data indicates
)41(5/ ss/
s/2v
Thank You
EOS
EOS
Elliptical flow v2
-v2 is sensitive to viscosity, especially shear viscosity
Qualitative effects of & on V2
Change the flow profile during hydro evolution
Flow + spectra correc.
ppf ~
Spectra correc.:
viscous hydro (shear only)
ideal hydro
viscous hydro (bulk only)
(with only flow correction here) A. Monnai talk : spectra correc. for bulk viscosity
Song & Heinz, 0909
EM probes: Photons
-Photon spectra are more sensitive to QGP shear viscosity than hadrons
Photon spectra
2T
Photon spectra
-Photon spectra may HELP to constrain QGP shear viscosity and hydro starting time
-Photon spectra are also sensitive to hydro starting time
-More sophisticated theoretical modeling in the future: including photon emitted from hadronic stage with modified photon emission rate, etc ; better experimental data
K. Dusling, 0903
-To describe the experimental data, one need to consider the contribution from all kinds of aspects besides shear viscosity