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Transcript of 1Erice 2012, Roy A. Lacey, Stony Brook University.
Is the QGP produced in LHC collisions more opaque than that produced in
RHIC collisions?
Roy A. LaceyChemistry Dept.,
Stony Brook University
1 Erice 2012, Roy A. Lacey, Stony Brook University
p
Conjectured Phase Diagram
2
Quantitative study of the QCD phase diagram is central to our field
Erice 2012, Roy A. Lacey, Stony Brook University
Interest
Location of the critical End point
Location of phase coexistence lines
Properties of each phase
All are fundamental to the phase diagram of any substanceSpectacular achievement:
Validation of the crossover transition leading to the QGP
Full characterization of the QGP is a central theme at RHIC and the LHC
Characterization of the QGP produced in RHIC and LHC collisions requires:
I. Development of experimental constraints to map the topological, thermodynamic and transport coefficients
II. Development of quantitative model descriptions of these properties
QGP Characterization?
Erice 2012, Roy A. Lacey, Stony Brook University3
ˆ( ), ( ), ( ), ( ), ( ), ( ), (B), etc ?s s sepT c T T T T q T
Experimental Access:
Temp/time-averaged constraints as
a function of √sNN (with similar expansion dynamics)
(I) Expect space-time averages to evolve with √sNN
ˆ, , , , , , etc ?s sT c qs s
(II)
4
RHIC (0.2 TeV) LHC (2.76 TeV) Power law dependence (n ~ 0.2) increase ~ 3.3 Multiplicity density increase ~ 2.3 <Temp> increase ~ 30%
The energy density lever armLacey et. al, Phys.Rev.Lett.98:092301,2007
Essential questions: How do the transport coefficients evolve with T?
Any indication for a change in coupling close to To?
ˆ, , ,s sc qs
Erice 2012, Roy A. Lacey, Stony Brook University
Energy scan
Take home message:The scaling properties of flow andJet quenching measurements give crucial new insights
The Flow Probe
s/
P ² Bj
, , /s, f, Ts fc
20
3
1 1
~ 5 45
TBj
dE
R dy
GeV
fm
5
( ) 1 2 cosn nYield a v n
Idealized Geometry
2 2
2 2
y x
y x
Crucial parameters
Actual collision profiles are not smooth, due to fluctuations!
Initial Geometry characterized by many shape harmonics (εn) drive vn
Initial eccentricity (and its attendant fluctuations) εn drive momentum anisotropy vn with specific scaling properties
22, exp 0
3
tT t k k T
s T
Acoustic viscous modulation of vn
Staig & Shuryak arXiv:1008.3139
Isotropic p
Anisotropic p
Erice 2012, Roy A. Lacey, Stony Brook University
Yield(f) =2 v2 cos[2( -f Y2]
KET & scaling validated for vn
Partonic flow /2n
qn
6
vn PID scaling
Flow is partonic @ RHIC
Erice 2012, Roy A. Lacey, Stony Brook University
7 Erice 2012, Roy A. Lacey, Stony Brook University
Flow increases from RHIC to LHC Sensitivity to EOS increase in <cs>
Proton flow blueshifted [hydro prediction] Role of radial flowRole of hadronic re-
scattering?
Flow increases from RHIC to LHC
8
Flow is partonic @ the LHC
Scaling for partonic flow validated after accounting for proton blueshift
Larger partonic flow at the LHC
KET (GeV)
0.5 1.0 1.5 0.5 1.0 1.5 0.5 1.0 1.5
10-20%
0.5 1.0 1.50.00
0.05
0.10
0.1520-30% 30-40% 40-50%
0.5 1.0 1.5
v 2/n
q
0.00
0.05
0.10
0.15
Kp
Pb+Pb @ 2.76 TeV 05-10%
Erice 2012, Roy A. Lacey, Stony Brook University
Hydrodynamic flow is acoustic
Characteristic n2 viscous damping for harmonics Crucial constraint for η/s
Associate k with harmonic n n
kR
9 Erice 2012, Roy A. Lacey, Stony Brook University
2 gR n
Note: the hydrodynamic response to the initial geometry [alone] is included
εn drive momentum anisotropy vn with modulation
22, exp 0
3
tT t k k T
s T
Modulation Acoustic
2expn
n
vn
Constraint for η/s & δf
Deformation n
kR
10
2
0
2
, exp 0
Particle Dist. ( )
( ) ~
T
TT
f
T t k n T
f f f p
pf p
T
Characteristic pT dependence of β reflects the influence of δf and η/s pT (GeV/c)
0 1 2 3 (
p T)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
4s = 1.25
(pT)-1/2
4s = 0.04s = 1.25 f~pT
1.5
20-30%
Hydro - Schenke et al.
Erice 2012, Roy A. Lacey, Stony Brook University
ATLAS-CONF-2011-074
11
High precision double differential Measurements are pervasiveDo they scale?
Erice 2012, Roy A. Lacey, Stony Brook University
vn(ψn) Measurements - ATLAS
Acoustic Constraint
Characteristic viscous dampingof the harmonics validatedImportant constraint
Wave numbern
kR
12
2 gR n LHCRHIC
2expn
n
vn
1~
4s
Erice 2012, Roy A. Lacey, Stony Brook University
arXiv:1105.3782
at RHIC; small increase for LHC
22, exp 0
3
tT t k k T
s T
13 Erice 2012, Roy A. Lacey, Stony Brook University
2 4 6
v n/ n
0.01
0.1
1 10-20%
n2 4 6
20-30%
2 4 6
30-40%
2 4 6
v n/ n
0.01
0.1
140-50%
Pb+Pb - 2.76 TeV
pT = 1.1 GeV/c
Acoustic Scaling 2expn
n
vn
β is essentially independent of centrality for a broad centrality range
15 30 45
0.00
0.05
0.10
0.15
0.20
0.25
pT = 1.1 GeV/c
Pb+Pb - 2.76 TeV
Centrality (%)
14
2 4 6
v n/ n
0.01
0.1
1
0.7 GeV/c
n2 4 6
1.3 GeV/c
2 4 6
1.9 GeV/c
2 4 6
v n/ n
0.01
0.1
1
2.3 GeV/c
Pb+Pb - 2.76 TeV
20-30%
2expn
n
vn
β scales as 1/√pT Important constraint
Erice 2012, Roy A. Lacey, Stony Brook University
Constraint for η/s & δf
<η/s> ~ 1/4π at RHIC; small increase for LHC
Scaling properties of Jet Quenching
Erice 2012, Roy A. Lacey, Stony Brook University 15
16 Erice 2012, Roy A. Lacey, Stony Brook University
Jet suppression Probe
AAAA
binary AA pp
YieldR ( , )
N YieldTp L
2( , ) [1 2 ( )cos(2 )]T TYield p v p
2
AA 20
AA 2
(90 , ) 1 2 ( )( , )
(0 , ) 1 2 ( )
oT T
TT T
R p v pR p L
R p v p
Suppression (∆L) – pp yield unnecessary
Jet suppression drives RAA & azimuthal anisotropy with specific scaling properties
Suppression (L)
, Phys.Lett.B519:199-206,2001
For Radiative Energy loss:
0
LcIT e
I
Modified jet
Moresuppression
Lesssuppression
Fixed Geometry
Path length(related to collision
centrality)
17
Geometric Quantities for scaling
A B
Geometric fluctuations included Geometric quantities constrained by multiplicity density.
~
L R
L R
*cosn nn
Phys. Rev. C 81, 061901(R) (2010)
arXiv:1203.3605
σx & σy RMS widths of density distribution
Erice 2012, Roy A. Lacey, Stony Brook University
RAA Measurements - CMS
Specific pT and centrality dependencies – Do they scale?
18
Eur. Phys. J. C (2012) 72:1945 arXiv:1202.2554
Centralitydependence
pT dependence
Erice 2012, Roy A. Lacey, Stony Brook University
L scaling of Jet Quenching - LHC
RAA scales with L, slopes (SL) encodes info on αs and qCompatible with the dominance of radiative energy loss
19
arXiv:1202.5537
ˆ
, Phys.Lett.B519:199-206,2001
Erice 2012, Roy A. Lacey, Stony Brook University
20
Phys.Rev.C80:051901,2009
Erice 2012, Roy A. Lacey, Stony Brook University
L scaling of Jet Quenching - RHIC
RAA scales with L, slopes (SL) encodes info on αs and qCompatible with the dominance of radiative energy loss
ˆ
RAA scales as 1/√pT ; slopes (SpT) encode info on αs and q L and 1/√pT scaling single universal curveCompatible with the dominance of radiative energy loss
21
arXiv:1202.5537
pT scaling of Jet Quenching
ˆ
, Phys.Lett.B519:199-206,2001
Erice 2012, Roy A. Lacey, Stony Brook University
High-pT v2 measurements - CMS
Specific pT and centrality dependencies – Do they scale?
22
arXiv:1204.1850
pT dependence
Centralitydependence
Erice 2012, Roy A. Lacey, Stony Brook University
Specific pT and centrality dependencies – Do they scale?
23 Erice 2012, Roy A. Lacey, Stony Brook University
0 5 10
v 2
0.00
0.05
0.10
0.15
0.20
0.25
10 - 20%
Au+Au @ 0.2 TeV
pT (GeV/c)0 5 10
20 - 30%
0 5 100.00
0.05
0.10
0.15
0.20
0.2530 - 40%
High-pT v2 measurements - PHENIX
pT dependence
Centrality dependence
24
High-pT v2 scaling - LHC
v2 follows the pT dependence observed for jet quenchingNote the expected inversion of the 1/√pT dependence
arXiv:1203.3605
Erice 2012, Roy A. Lacey, Stony Brook University
pT-1/2 (GeV/c)-1/2
0.2 0.3 0.4 0.5
v 2
0.0
0.1
0.2
10 - 20 (%)20 - 3030 - 40
0.2 0.3 0.4 0.5
v 2/
L (
fm-1
)
0.0
0.2
0.4
Au+Au @ 0.2 TeV
25
∆L Scaling of high-pT v2 – LHC & RHIC
Combined ∆L and 1/√pT scaling single universal curve for v2
arXiv:1203.3605
Erice 2012, Roy A. Lacey, Stony Brook University
Npart
0 100 200 300
v 2/
L
0.0
0.5
v 2
0.0
0.1
0.2 6 < pT < 9 (GeV/c)
pT > 9
pT-1/2 (GeV/c)-1/2
0.2 0.4 0.6
v 2/
L
0.0
0.2
0.4
10 - 20 (%)20 - 3030 - 40
Au+Au @ 0.2 TeV
26 Erice 2012, Roy A. Lacey, Stony Brook University
∆L Scaling of high-pT v2 - RHIC
Combined ∆L and 1/√pT scaling single universal curve for v2
Constraint for εn
(pTJet)-1/2 (GeV/c)-1/2
0.05 0.10 0.15
v 2Je
t
0.00
0.05
0.10
10-20 (%)20-30 30-40 40-50
Pb+Pb @ 2.76 TeV
27
Jet v2 scaling - LHC
v2 for reconstructed Jets follows the pT dependence for jet quenchingSimilar magnitude and trend for Jet and hadron v2 after scaling
Erice 2012, Roy A. Lacey, Stony Brook University
pT-1/2 (GeV/c)-1/2
0.1 0.2 0.3
v 2
-0.05
0.00
0.05
0.10
0.15Jet - ATLASHadron - CMS
pT-1/2 (GeV/c)-1/2
0.1 0.2 0.3
v 2
-0.05
0.00
0.05
0.10
0.15Jet - ATLASHadrons - CMSHadrons - scaled (z ~ .62)
ATLAS
28
Jet suppression from high-pT v2
Jet suppression obtained directly from pT dependence of v2
arXiv:1203.3605
2( , ) [1 2 ( )cos(2 )]T TN p v p
2
AA 20
AA 2
(90 , ) 1 2 ( )( , )
(0 , ) 1 2 ( )
oT T
v TT T
R p v pR p L
R p v p
Rv2 scales as 1/√pT , slopes encodes info on αs and q̂
Erice 2012, Roy A. Lacey, Stony Brook University
0.2 0.4
ln(R
2)
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.210 - 20%
pT-1/2 (GeV/c)-1/2
0.2 0.4
20 - 30%
0.2 0.4
30 - 40%
pT-1/2 (GeV/c)-1/2
0.2 0.4
ln(R
2)/
L [f
m-1
]
-2.0
-1.5
-1.0
-0.5
0.0
0.5
10 - 20 (%)20 - 3030 - 40
Au+Au @ 0.2 TeV
29 Erice 2012, Roy A. Lacey, Stony Brook University
Jet suppression from high-pT v2 - RHIC2
AA 20
AA 2
(90 , ) 1 2 ( )( , )
(0 , ) 1 2 ( )
oT T
v TT T
R p v pR p L
R p v p
Jet suppression obtained directly from pT dependence of v2
R2 scales as 1/√pT , slopes encodes info on αs and ˆq
L (fm)0.5 1.0 1.5 2.0
ln(R
AA)
-1.5
-1.0
-0.5
0.0D (prompt)6 - 12 GeV/c
Pb+Pb @ 2.76 TeV
ALICE
Consistent obtained
30 Erice 2012, Roy A. Lacey, Stony Brook University
qLHC ˆ
Heavy quark suppression
31
Extracted stopping power
2
ˆ ~ 0.75 RHIC
GeVq
fm
Phys.Rev.C80:051901,2009
2
ˆ ~ 0.56 LHC
GeVq
fm
obtained from high-pT v2 and RAA [same αs] similar - medium produced in LHC collisions less opaque!
arXiv:1202.5537 arXiv:1203.3605
Conclusion similar to those of Liao, Betz, Horowitz, Stronger coupling near Tc?
qRHIC > qLHCˆqLHC ˆ
Erice 2012, Roy A. Lacey, Stony Brook University
Remarkable scaling have been observed for both Flow and Jet Quenching
They lend profound mechanistic insights, as well as New constraints forestimates of the transport and thermodynamic coefficients!
32
RAA and high-pT azimuthal anisotropy stem from the same energy loss mechanism
Energy loss is dominantly radiative
RAA and anisotropy measurements give consistent estimates for <ˆq >
RAA for D’s give consistent estimates for <ˆq >
The QGP created in LHC collisions is less opaque than that produced at RHIC
Flow is acousticFlow is pressure driven Obeys the dispersion relation
for sound propagation Flow is partonic
exhibits scalingConstraints for:
initial geometry η/s similar at LHC and RHIC ~
1/4π
What do we learn?
/2 n, 2, /2
vv ( ) ~ v or
( )n
n q T q nq
KEn
Summary
Erice 2012, Roy A. Lacey, Stony Brook University
End
33Erice 2012, Roy A. Lacey, Stony Brook University
34
Flow @ RHIC and the LHC
Erice 2012, Roy A. Lacey, Stony Brook University
Multiplicity-weighted PIDed flow results reproduce inclusive charged hadron flow
results at RHIC and LHC respectively
Charge hadron flow similar @ RHIC & LHC
35 Erice 2012, Roy A. Lacey, Stony Brook University
For partonic flow, quark number scaling expected single curve for identified particle species vn
Is flow partonic?
/2 n2 /2
vExpectation: v ( ) ~ v or
( )n
n T nq
KEn Note species dependence for all vn