Transcript 071026_AdSCFTDay_Zajc

Introduction
and
Welcome
AdS/CFT Intersects Nuclear Beams at Columbia
W.A. Zajc
Columbia University
26-Oct-07
W.A. Zajc
RHIC Perspectives
W.A. Zajc
Columbia University
26-Oct-07
W.A. Zajc
Outline of My Talk
26-Oct-07
W.A. Zajc
Really, It’s A Meta-Talk
Introduction,
Motivation,
Definition of
terms up to here
26-Oct-07
Two major discoveries:
Flow
Jet quenching
W.A. Zajc
Really, It’s A Meta-Talk
Flow,
v2 scaling with nq
26-Oct-07
W.A. Zajc
Really, It’s A Meta-Talk
Jet quenching,
away-side disappearance,
direct photons
26-Oct-07
Mach cones,
re-appearance of the away
side
W.A. Zajc
Really, It’s A Meta-Talk
26-Oct-07
Perfect liquid,
KSS bound as QM result
Viscosity primer
W.A. Zajc
Really, It’s A Meta-Talk
26-Oct-07
The dénouement!
AdS/CFT connection
h/s values
W.A. Zajc
The Primacy of QCD

While the (conjectured) bound
h 

s 4
is a purely quantum mechanical result . . .
It was derived in and motivated by
the Anti-de Sitter space / Conformal Field Theory correspondence

Weak form:

“Four-dimensional N=4 supersymmetric SU(Nc) gauge theory is
equivalent to IIB string theory with AdS5 x S5 boundary conditions.”
( The Large N limit of superconformal field theories and supergravity,
J. Maldacena, Adv. Theor. Math. Phys. 2, 231, 1998 hep-th/9711200 )

Strong form:

“Hidden within every non-Abelian gauge theory, even within the weak
and strong nuclear interactions, is a theory of quantum gravity.”
( Gauge/gravity duality, G.T. Horowitz and J. Polchinski, gr-qc/0602037 )

Strongest form: Only with QCD can we explore experimentally these
fascinating connections over the full range of the coupling constant
to study QGP  Quantum Gauge Phluid
26-Oct-07
W.A. Zajc
The (Assumed) Connection
Exploit

Maldacena’s
“D-dimensional strongly coupled gauge theory  (D+1)-dimensional
stringy gravity”
hmn
Thermalize with massive black brane

Calculate


Normalize by entropy (density)

Dividing out

Conjectured

Am
viscosity h = “Area”/16G
An Infinite
“Area” !
s = “Area” / 4G
the infinite “areas” :
h
 1
( )
s
k 4
to be a lower bound “for all relativistic quantum field
theories at finite temperature and zero chemical potential”.
See “Viscosity in strongly interacting quantum field theories from
black hole physics”, P. Kovtun, D.T. Son, A.O. Starinets,
Phys.Rev.Lett.94:111601, 2005, hep-th/0405231
26-Oct-07
W.A. Zajc
New Dimensions in RHIC Physics

“The stress tensor of a quark moving through N=4
thermal plasma”, J.J. Friess et al., hep-th/0607022
Our 4-d
world
String
theorist’s
5+5-d
world
26-Oct-07
The stuff formerly
known as QGP
Jet modifications
from wake field
Heavy quark
moving
through
the
Energy loss medium
from string
drag
W.A. Zajc
Measuring h/s

Damping (flow, fluctuations, heavy quark motion) ~ h/s

FLOW: Has the QCD Critical Point Been
Signaled by Observations at RHIC?,
R. Lacey et al.,
Phys.Rev.Lett.98:092301,2007
(nucl-ex/0609025)

The Centrality dependence of Elliptic flow,
the Hydrodynamic Limit, and the Viscosity
of Hot QCD, H.-J. Drescher et al.,
(arXiv:0704.3553)

C
H
A
R
M
!
26-Oct-07
FLUCTUATIONS: Measuring Shear Viscosity
Using Transverse Momentum Correlations
in Relativistic Nuclear Collisions,
S. Gavin and M. Abdel-Aziz,
Phys.Rev.Lett.97:162302,2006
(nucl-th/0606061)
DRAG, FLOW: Energy Loss and Flow of
Heavy Quarks in Au+Au Collisions
at √sNN = 200 GeV (PHENIX Collaboration),
A. Adare et al.,
to appear in Phys. Rev. Lett. (nucl-ex/0611018)
h
1
 (1.1  0.2  1.2)
s
4
h
1
 (1.9  2.5)
s
4
h
1
 (1.0  3.8)
s
4
h
1
 (1.3  2.0)
s
4
W.A. Zajc
Has the QCD Critical Point Been Signaled by Observations at RHIC?,
R. Lacey et al., Phys.Rev.Lett.98:092301,2007 (nucl-ex/0609025)
Signature: FLOW
Fit v2 ~I1(w)/I0(w); w
= mT/2T
h
 Calculation:
~ T f c s
s
On-shell transport model
for gluons, Z. Xu and
T  165  3 MeV

C. Greiner,
hep-ph/0406278.
c s  0.35  0.05
 f  0.3  0.03 fm

Payoff Plot:
26-Oct-07
h
1
  (1.1  0.2  1.2)
s
4
PHENIX v2/e data
(nucl-ex/0608033)
compared to R.S.
Bhalerao et al.
(nucl-th/0508009)
W.A. Zajc
Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear
Collisions, S. Gavin and M. Abdel-Aziz, Phys.Rev.Lett.97:162302,2006 (nucl-th/0606061)


Signature: FLUCTUATIONS
  h 2
Calculation:
 g  0
 
Difference in
correlation widths
for central and
peripheral
collisions
 t
 0
2

sT
2
4h 1

sT  f
  f  0 


 0 
4h  1
1 
c  p 



sT  f

f
P
C 

 f , P ~ 1 fm ,  f , C ~ 20 fm
2
Diffusion eq. for
fluctuations g
Compare to STAR
data on centrality
dependence of
rapidity width  of
pT fluctuations
2
h

Payoff Plot:
26-Oct-07
1
  (1  3.8)
s
4
W.A. Zajc
The Centrality dependence of Elliptic flow, the Hydrodynamic Limit, and
the Viscosity of Hot QCD, H.-J. Drescher et al., (arXiv:0704.3553)


Signature: FLOW
Calculation: 1  R   R   1 1 dN  (c S )   dN c S
 A  dy 
K 
A dy


Knudsen
number K


1
 v2 


 

e  e  perfect  1  K / K 0 
K 0  0.7 , c S  1/ 3 ,


Payoff Plot:
26-Oct-07
Decrease in flow
due to finite size
v2
h
s
 (1.9  2.5)
1
4
h  1.264 T / 
, s  4n
Fits to PHOBOS
v2 data to
determine  for
Glauber and
CGC initial
conditions
W.A. Zajc
Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √s NN = 200 GeV (PHENIX
Collaboration), A. Adare et al., Phys. Rev. Lett. 98:172301,2007 (nucl-ex/0611018)


Signature: FLOW, ENERGY LOSS
Calculation: DHQ ~ (4  6) 2 T
Rapp and van Hees
Phys.Rev.C71:034
907,2005, to fit
both PHENIX
v2(e) and RAA(e)

DHQ / h /(e  P )  ~ 6 for N f  3
h
1
  (1.3  2.0)
s
4
Moore and Teaney
Phys.Rev.C71:064
904,2005
(perturbative,
argue ~valid
non-perturbatively)
Payoff Plot:
26-Oct-07
W.A. Zajc
(Some) Things I’d Like To Know



Are there better ways to extract h/s ?
Can these existing estimates be improved ?
(In particular, can systematic errors be understood?)
All of these methods rely on e+P = Ts .
How does this change in the presence of a conserved
charge ?

In ordinary fluids, h/s has a pronounced minimum near
the critical point.
Can AdS/CFT say anything about this for gauge fluids?

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W.A. Zajc
(More) Things I’d Like To Know

Are AdS/CFT predictions falsifiable ?

What if Song and Heinz h/s < 1/4 is correct?

Suppression of elliptic flow in a minimally viscous quark-gluon plasma,
H. Song and U. Heinz, arXiv:0709.0742v1 .




What if Mach cone angles different from data ?
What if 1/√g not seen in J/Y suppression ?
What data can best constrain initial conditions?
(Will we ever be able to eliminate this source of ambiguity
between Glauber, CGC, … ?)
Are there AdS/CFT setups to do elliptic flow dynamically?
Can they say anything about the observed scaling ?

26-Oct-07
W.A. Zajc
The “Flow” Is ~ Perfect

The “fine structure” v2(pT) for different mass particles
shows good agreement with ideal (“perfect fluid”)
hydrodynamics
KET  m2  pT

2
Roughly: ∂nTmn =0  Work-energy theorem
  P d(vol) = DEK  mT – m0  DKET
26-Oct-07
W.A. Zajc
The “Flow” Knows Quarks

The “fine structure” v2(pT) for different mass particles
shows good agreement with ideal (“perfect fluid”)
hydrodynamics
baryons
mesons

Scaling flow parameters by quark content nq resolves
meson-baryon separation of final state hadrons
26-Oct-07
W.A. Zajc
(More) Things I’d Like To Know

What does flow scaling tell us about degrees of freedom?

Hadronic Modes and Quark Properties in the Quark-Gluon Plasma,
M. Mannarelli and R. Rapp, arXiv:hep-ph/0505080v2 :
m ~ 150 MeV , G ~ 200 MeV .
Is any form of quasiparticle consistent with KSS bound?

All(?) AdS/CFT calculations find drag ~ √ = √g2NC .
What is this telling us about the degrees of freedom ?

Is there a unique prescription for fixing coupling ?

Is there well-controlled expansion away from ‘t Hooft limit?
 Calibrate it with lattice ‘data’ ?
ASIDE: Those who most often pronounce “AdS/CFT is useless
because the coupling doesn’t run” are those most likely to do
calculations with as = 0.5 .

26-Oct-07
W.A. Zajc
(Big ) Things I’d Like To Know


Can one start from confining, chiral Sakai-Sugimoto and
push it through a phase transition ?
Hod tells us  > 1 /  T.

Universal Bound on Dynamical Relaxation Times and Black-Hole
Quasinormal Ringing, S. Hod, arXiv:gr-qc/0611004v1
Can AdS/CFT address this ?
What does it mean to have a gravity dual ?
In particular, how do I find it ?

What is the impact of the KSS conjecture on other fields ?
26-Oct-07
W.A. Zajc
What Follows is the Un-Meta-Talk…
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W.A. Zajc
Working Title: The Fluid Nature of QGP

From the Oxford English Dictionary:
1) Primary definition: (adj.) fluid :
"Having the property of flowing; consisting of particles that move
freely among themselves, so as to give way before the slightest
pressure. (A general term including both gaseous and liquid
substances.)”
2) Secondary definition: (adj.)
"Flowing or moving readily; not solid or rigid;
not fixed, firm, or stable.”

SUMMARY: Following
a) a discovery period, during which time our
understanding of “quark-gluon plasma” was fluid(2),
and
b) a paradigm shift,
we are now developing a solid understanding
of the extraordinary fluid(1) produced at RHIC.
26-Oct-07
W.A. Zajc
Expectations circa 2000
RHIC would create
a quark-gluon plasma;
a “gas” of weakly
interacting
quarks and gluons
As encoded in the Nuclear Physics Wall Chart,
26-Oct-07
http://www.lbl.gov/abc/wallchart/
W.A. Zajc
The Plan circa 2000

Use RHIC’s unprecedented capabilities

Large √s 
 Access
to reliable pQCD probes
 Clear separation of valence baryon number and glue
 To provide definitive experimental evidence for/against
Quark Gluon Plasma (QGP)


Polarized p+p collisions
See earlier talk by M. Grosse Perdekamp
Two small detectors, two large detectors
Complementary capabilities
 Small detectors envisioned to have 3-5 year lifetime
 Large detectors ~ facilities

 Major
capital investments
 Longer lifetimes
 Potential for upgrades in response to discoveries
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W.A. Zajc
RHIC and Its Experiments
STAR
26-Oct-07
W.A. Zajc
Since Then…

Accelerator complex


Routine operation at 2-4 x design luminosity (Au+Au)
Extraordinary variety of operational modes
Species: Au+Au, d+Au, Cu+Cu, p+p
 Energies: 22 GeV (Au+Au, Cu+Cu, p), 56 GeV (Au+Au),
62 GeV (Au+Au,Cu+Cu, p+p)
, 130 GeV (Au+Au),
200 GeV (Au+Au, Cu+Cu, d+Au, p+p), 410 GeV (p), 500 GeV (p)


Experiments:


Science



Worked !
>160 refereed publications, among them > 90 PRL’s
Major discoveries
Future



26-Oct-07
Demonstrated ability to upgrade
Key science questions identified
Accelerator and experimental upgrade program
underway to perform that science
W.A. Zajc
Approach
Will present sample of results from various
points of the collision process:
2. Initial State
Hydrodynamic flow
from
initial spatial asymmetries
1. Final State
Yields of produced particles
Thermalization, Hadrochemistry
3. Probes of
dense
matter
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W.A. Zajc
Assertion

In these complicated events, we have
(a posteriori ) control over the event geometry:

Degree of overlap
“Central”

26-Oct-07
“Peripheral”
Orientation with respect to overlap
W.A. Zajc
Language

We all have in common basic nuclear properties


A, Z …
But specific to heavy ion physics
v2
 RAA
 T
 mB
 h
 s

26-Oct-07
Fourier coefficient of azimuthal anisotropies  “flow”
1 if yield = perturbative value from initial parton-parton flux
Temperature (MeV)
Baryon chemical potential (MeV) ~ net baryon density
Viscosity ( MeV 3 )
Entropy density ( MeV 3 ) ~ “particle” density
W.A. Zajc
Final State
Does the huge abundance of final state
particles reflect a thermal distribution?:
1. Final State
Yields of produced particles
Thermalization, Hadrochemistry
Consistent with
thermal production
26-Oct-07
T ~ 170 MeV , mB ~ 30 MeV
W.A. Zajc
RHIC’s Two Major Discoveries


Discovery of
strong “elliptic” flow:

Elliptic flow in Au + Au collisions at
√sNN= 130 GeV,
STAR Collaboration, (K.H.
Ackermann et al.).
Phys.Rev.Lett.86:402-407,2001

318 citations
Discovery of
“jet quenching”

Suppression of hadrons with large
transverse momentum in central
Au+Au collisions at √sNN = 130 GeV,
PHENIX Collaboration (K. Adcox et
al.), Phys.Rev.Lett.88:022301,2002

384 citations
26-Oct-07
W.A. Zajc
Initial State
How are the initial state densities and asymmetries
imprinted on the detected distributions?
3. Initial State
Hydrodynamic flow
from
initial spatial asymmetries
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W.A. Zajc
Motion Is Hydrodynamic

When does thermalization occur?


Strong evidence that final state bulk behavior
reflects the initial state geometry
Because the initial azimuthal asymmetry
persists in the final state
dn/df ~ 1 + 2 v2(pT) cos (2 f) + ...
z
y
x
2v2
26-Oct-07
W.A. Zajc
The “Flow” Is ~ Perfect

The “fine structure” v2(pT) for different mass particles
shows good agreement with ideal (“perfect fluid”)
hydrodynamics
KET  m2  pT

2
Roughly: ∂nTmn =0  Work-energy theorem
  P d(vol) = DEK  mT – m0  DKET
26-Oct-07
W.A. Zajc
The “Flow” Knows Quarks

The “fine structure” v2(pT) for different mass particles
shows good agreement with ideal (“perfect fluid”)
hydrodynamics
baryons
mesons

Scaling flow parameters by quark content nq resolves
meson-baryon separation of final state hadrons
26-Oct-07
W.A. Zajc
Probes of Dense Matter
Q. How dense is the matter?
A. Do pQCD Rutherford scattering on deep interior using
“auto-generated” probes:
2. Probes of
dense
matter
26-Oct-07
W.A. Zajc
Baseline p+p Measurements with pQCD


Consider measurement of 0’s in p+p
collisions at RHIC.
Compare to pQCD calculation
d  fa / A( xa, m 2 )  fb / B ( xb, m 2 )
•parton distribution functions,
for partons a and b
•measured in DIS, universality

 d  (a  b  c  d )
•perturbative cross-section (NLO)
•requires hard scale
•factorization between pdf and cross
section
 Dh / c ( zh, m 2 )
•fragmentation function
•measured in e+e
Phys. Rev. Lett. 91, 241803 (2003)
26-Oct-07
W.A. Zajc
Enhanced
Au+Au: Systematic Suppression Pattern
Suppressed

26-Oct-07
 constancy for pT > 4 GeV/c for all centralities?
W.A. Zajc
The Matter is Opaque

STAR azimuthal
correlation
function shows
~ complete
absence of
“away-side” jet
GONE
DF = 
DF
Partner in hard scatter is
completely absorbed
in the dense medium
DF=0
DF = 0
26-Oct-07
W.A. Zajc
Schematically (Partons)
Scattered partons on the “near side” lose energy,
but emerge;
those on the “far side” are totally absorbed
26-Oct-07
W.A. Zajc
Control: Photons shine, Pions don’t
 Direct photons are
not inhibited by hot/dense medium
 Rather: shine through consistent with pQCD
26-Oct-07
W.A. Zajc
Schematically (Photons)
Scattered partons on the “near side” lose energy,
but emerge;
the direct photon always emerges
26-Oct-07
W.A. Zajc
Precision Probes

This one figure encodes
rigorous control of systematics
central
Ncoll = 975  94
=

26-Oct-07
=
in four different measurements
over many orders of magnitude
W.A. Zajc
Connecting Soft and Hard Regimes
Scattered partons on the “near side” lose energy,
but emerge;
those on the “far side” are totally absorbed
26-Oct-07
 Really ?
W.A. Zajc
Fluid Effects on Jets ?

Mach cone?
☑ Jets travel faster than the
speed of sound in the
medium.
☑ While depositing energy
via gluon radiation.
QCD “sonic boom” (?)
To be expected
in a dense fluid
which is
strongly-coupled
26-Oct-07
W.A. Zajc
High pT Parton  Low pT “Mach Cone”?




The “disappearance”
is that of the
high pT partner
But at low pT,
see re-appearance
and
“Side-lobes”
(Mach cones?)
26-Oct-07
W.A. Zajc
Suggestion of Mach Cone?

Modifications to di-jet hadron pair correlations in Au+Au collisions at √s NN = 200 GeV,
PHENIX Collaboration (S.S. Adler et al.), Phys.Rev.Lett.97:052301,2006
A “perfect”
fluid
response!
DF
26-Oct-07
W.A. Zajc
How Perfect is “Perfect” ?

All “realistic” hydrodynamic calculations for RHIC fluids to
date have assumed zero viscosity
 h = 0  “perfect fluid”

But there is a (conjectured) quantum limit:
“A Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231


( Entropy Density) 
s
4
4

Where do
“ordinary”
fluids sit wrt
this limit?

RHIC “fluid” might
be at ~1 on this
scale (!)
26-Oct-07
(4
h
T=1012
K
W.A. Zajc
Viscosity Primer

Remove your organic prejudices


Don’t equate viscous with “sticky” !
Think instead of a not-quite-ideal fluid:



“not-quite-ideal”  “supports a shear stress”
Fx
v x
Viscosity h
 h
then defined as
A
y
Dimensional
estimate:
η  (momentum density)  (mean
free path)
1
p
 n p mfp  n p

nσ σ
 small viscosity  Large cross sections
Large cross sections  strong couplings
Strong couplings  perturbation theory difficult !
26-Oct-07
W.A. Zajc
The Primacy of QCD

While the (conjectured) bound
h 

s 4
is a purely quantum mechanical result . . .
It was derived in and motivated by
the Anti-de Sitter space / Conformal Field Theory correspondence

Weak form:

“Four-dimensional N=4 supersymmetric SU(Nc) gauge theory is
equivalent to IIB string theory with AdS5 x S5 boundary conditions.”
( The Large N limit of superconformal field theories and supergravity,
J. Maldacena, Adv. Theor. Math. Phys. 2, 231, 1998 hep-th/9711200 )

Strong form:

“Hidden within every non-Abelian gauge theory, even within the weak
and strong nuclear interactions, is a theory of quantum gravity.”
( Gauge/gravity duality, G.T. Horowitz and J. Polchinski, gr-qc/0602037 )

Strongest form: Only with QCD can we explore experimentally these
fascinating connections over the full range of the coupling constant
to study QGP  Quantum Gauge Phluid
26-Oct-07
W.A. Zajc
The (Assumed) Connection
Exploit

Maldacena’s
“D-dimensional strongly coupled gauge theory  (D+1)-dimensional
stringy gravity”
hmn
Thermalize with massive black brane

Calculate


Normalize by entropy (density)

Dividing out

An Infinite
“Area” !
s = “Area” / 4G
the infinite “areas” :
See next talk:
QGP- Theoretical Overview, U. Wiedemann

Am
viscosity h = “Area”/16G
h
 1
( )
s
k 4
Conjectured
to be a lower bound “for all relativistic quantum field
theories at finite temperature and zero chemical potential”.
See “Viscosity in strongly interacting quantum field theories from
black hole physics”, P. Kovtun, D.T. Son, A.O. Starinets,
Phys.Rev.Lett.94:111601, 2005, hep-th/0405231
26-Oct-07
W.A. Zajc
New Dimensions in RHIC Physics

“The stress tensor of a quark moving through N=4
thermal plasma”, J.J. Friess et al., hep-th/0607022
Our 4-d
world
String
theorist’s
5+5-d
world
26-Oct-07
The stuff formerly
known as QGP
Jet modifications
from wake field
Heavy quark
moving
through
the
Energy loss medium
from string
drag
W.A. Zajc
Measuring h/s

Damping (flow, fluctuations, heavy quark motion) ~ h/s

FLOW: Has the QCD Critical Point Been
Signaled by Observations at RHIC?,
R. Lacey et al.,
Phys.Rev.Lett.98:092301,2007
(nucl-ex/0609025)

The Centrality dependence of Elliptic flow,
the Hydrodynamic Limit, and the Viscosity
of Hot QCD, H.-J. Drescher et al.,
(arXiv:0704.3553)

C
H
A
R
M
!
26-Oct-07
FLUCTUATIONS: Measuring Shear Viscosity
Using Transverse Momentum Correlations
in Relativistic Nuclear Collisions,
S. Gavin and M. Abdel-Aziz,
Phys.Rev.Lett.97:162302,2006
(nucl-th/0606061)
DRAG, FLOW: Energy Loss and Flow of
Heavy Quarks in Au+Au Collisions
at √sNN = 200 GeV (PHENIX Collaboration),
A. Adare et al.,
to appear in Phys. Rev. Lett. (nucl-ex/0611018)
h
1
 (1.1  0.2  1.2)
s
4
h
1
 (1.9  2.5)
s
4
h
1
 (1.0  3.8)
s
4
h
1
 (1.3  2.0)
s
4
W.A. Zajc
Has the QCD Critical Point Been Signaled by Observations at RHIC?,
R. Lacey et al., Phys.Rev.Lett.98:092301,2007 (nucl-ex/0609025)
Signature: FLOW
Fit v2 ~I1(w)/I0(w); w
= mT/2T
h
 Calculation:
~ T f c s
s
On-shell transport model
for gluons, Z. Xu and
T  165  3 MeV

C. Greiner,
hep-ph/0406278.
c s  0.35  0.05
 f  0.3  0.03 fm

Payoff Plot:
26-Oct-07
h
1
  (1.1  0.2  1.2)
s
4
PHENIX v2/e data
(nucl-ex/0608033)
compared to R.S.
Bhalerao et al.
(nucl-th/0508009)
W.A. Zajc
Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear
Collisions, S. Gavin and M. Abdel-Aziz, Phys.Rev.Lett.97:162302,2006 (nucl-th/0606061)


Signature: FLUCTUATIONS
  h 2
Calculation:
 g  0
 
Difference in
correlation widths
for central and
peripheral
collisions
 t
 0
2

sT
2
4h 1

sT  f
  f  0 


 0 
4h  1
1 
c  p 



sT  f

f
P
C 

 f , P ~ 1 fm ,  f , C ~ 20 fm
2
Diffusion eq. for
fluctuations g
Compare to STAR
data on centrality
dependence of
rapidity width  of
pT fluctuations
2
h

Payoff Plot:
26-Oct-07
1
  (1  3.8)
s
4
W.A. Zajc
The Centrality dependence of Elliptic flow, the Hydrodynamic Limit, and
the Viscosity of Hot QCD, H.-J. Drescher et al., (arXiv:0704.3553)


Signature: FLOW
Calculation: 1  R   R   1 1 dN  (c S )   dN c S
 A  dy 
K 
A dy


Knudsen
number K


1
 v2 


 

e  e  perfect  1  K / K 0 
K 0  0.7 , c S  1/ 3 ,


Payoff Plot:
26-Oct-07
Decrease in flow
due to finite size
v2
h
s
 (1.9  2.5)
1
4
h  1.264T / 
, s  4n
Fits to PHOBOS
v2 data to
determine  for
Glauber and
CGC initial
conditions
W.A. Zajc
Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √s NN = 200 GeV (PHENIX
Collaboration), A. Adare et al., Phys. Rev. Lett. 98:172301,2007 (nucl-ex/0611018)


Signature: FLOW, ENERGY LOSS
Calculation: DHQ ~ (4  6) 2 T
Rapp and van Hees
Phys.Rev.C71:034
907,2005, to fit
both PHENIX
v2(e) and RAA(e)

DHQ / h /(e  P )  ~ 6 for N f  3
h
1
  (1.3  2.0)
s
4
Moore and Teaney
Phys.Rev.C71:064
904,2005
(perturbative,
argue ~valid
non-perturbatively)
Payoff Plot:
26-Oct-07
W.A. Zajc
RHIC and the Phase “Transition”


The lattice tells us that collisions at RHIC map out the
interesting region from
High Tinit
~ 300 MeV
?
to

Low Tfinal
~ 100 MeV
Recall per
massless
degree of
freedom
e (T )
T
26-Oct-07
4

2
30
W.A. Zajc
LHC



How could we not choose to investigate “QGP” at every
opportunity?
LHC offers unparalleled
increase in √s
Will this too create a
strongly-coupled fluid?

Active pursuit via


26-Oct-07
Dedicated experiment (ALICE)
Targeted studies (CMS, ATLAS)
W.A. Zajc
World Context
: 2009
: 2000RHIC II 
: 2012
26-Oct-07
W.A. Zajc
Physics for Many INPC’s To Come!
RHIC  RHIC II

LHC
Exploration


~ Completed
Discovery!

Preparation
GSI-FAIR





Characterization



Photon+Jet
Heavy Flavor
Energy Scans


(Anticipation)
Exploration


~ Completed
Discovery!
Preparation





(Anticipation)
Exploration


Exploitation
(of upgrade potential)
 Source
 Detectors
 Luminosity
26-Oct-07

Characterization



Photon+Jet
Heavy Flavor
Energy Scans


~ Completed
Discovery!
Characterization


Photon+Jet
Heavy Flavor
W.A. Zajc