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Poster xxx, Quark Matter 2005
Bulk-medium Proper ties in Relativistic Nuclear CollisionsDuncan Prindle University of Washington (STAR Collaboration)
Supported in part by the Office of Science of the U. S. Department of Energy
Recoil Response to Parton Stopping Same-side Medium Recoil Summary• Net-charge correlations reveal changing dimension of
hadronization geometry – large-amplitude correlations
• Number correlations on pt, yt reveal medium response to parton dissipation – thermal/velocity structure on (η,φη,φη,φη,φ)
• pt correlations on (η,φη,φη,φη,φ) inferred from ����pt���� fluctuations reveal recoil response of the medium to parton stopping
Two-particle correlations on pt⊗⊗⊗⊗pt and yt⊗⊗⊗⊗yt Number Correlations on pt⊗⊗⊗⊗pt Number Correlations on yt⊗⊗⊗⊗yt
Au-Au CD Correlations – 62 GeV Interpretation Low-Q2 partons probe the Au-Au Medium
Properties of the Bulk Medium p-p CD Correlations – 200 GeV Au-Au CD Correlations – 130 GeV
Interpretation �pt� Fluctuations and pt Correlations pt Correlations: Model Fits
what is the geometry of the hadronization process?what is the local velocity structure of the mediumin response to parton dissipation (bremsstrahlung)?
what is the collective response of the medium toparton stopping? each question can be addressedwith two-particle number or pt correlations
Transverse-momentum correlations on pseudorapidity and azimuth sug-
gest that the bulk medium recoils collectively in response to parton stop-ping. Charge-dependent number correlations reveal qualitative change of
hadronization geometry with centrality: from 1D string fragmentation inp-p to 2D bulk fragmentation in Au-Au collisions.
[1] J. Adams et al. (STAR Collaboration), nucl-ex/0406035, nucl-ex/0408012,nucl-ex/0411003.
Correlation measurements with hadron pt < 2 GeV/c in Au-Au collisions
at 130 GeV has provided qualitatively new information about heavy ioncollisions [1]. We now present a broad survey of two-particle number and
transverse-momentum correlations from Au-Au collisions at 62, 130 and200 GeV which probe dynamical properties of the dissipative bulk medium.
Charge-independent number correlations on transverse rapidity reveal thetemperature/velocity structure resulting from parton dissipation.
hadronization geometry
-2-1.5
-1-0.5
00.5
11.5
2
-10
12
34
-0.004
-0.002
0
0.002
ρρ∆
∆φ ∆η
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
0
0.0010.0020.0030.0040.005
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
(d)
X(pt1)
r
ˆ -
1
X(pt2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.0020
0.0020.0040.0060.008
0.010.0120.014
(b)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.1-0.05
00.050.1
0.150.2
x 10-2
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
0.010.0120.0140.0160.0180.02
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
η ∆
φ∆
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
-0.003-0.002-0.001
00.0010.0020.0030.0040.0050.006
-2
-1
0
1
2
02
4
-0.01-0.008-0.006-0.004-0.002
00.0020.0040.006
local thermal/velocity structure
bulk-medium recoil: response to parton stopping
yt
∆ρ /
√ρre
f
y t
1
2
3
4
51
23
45
00.005
0.010.015
0.020.025
0.030.035
Au-Au
yt
∆ρ /
√ρre
f
y t
1
2
3
4
51
23
45
-0.05-0.04-0.03-0.02-0.0100.010.020.03
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
φ∆
η ∆
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
0 2 4
AS – away side
STAR preliminary
{ }0ln ( ) /t t ty m p m≡ +
yt1
y t2
1
1.5
2
2.5
3
3.5
4
4.5
1 2 3 4
PF
SF
φ∆
∆ρ /
√ρre
f
η ∆
02
4
-2
-1
0
1
2
-0.3-0.2-0.1
00.10.20.30.40.50.60.7
PF – parton fragments
φ∆
∆ρ /
√ρre
f
η ∆
02
4
-2
-1
0
1
2
-0.2-0.1
00.10.20.3
SF – string fragments
yt
∆ρ /
√ρre
f y t
1
2
3
4
51
23
45
-0.03-0.02-0.0100.010.020.030.040.050.06 SS – same side
transverse rapidity
200 GeV
1D charge orderingon z,ηηηη or yz
1D charge orderingon pt or yt (thrust)
CD=LS-US: charge-dependent or net-charge
η∆∆∆∆
J. Adams et al. (STAR), nucl-ex/0406035
φ∆
∆ρ /
√ρre
f
η ∆
02
4
-2
-1
0
1
2
-0.3-0.2-0.1
00.10.20.30.40.50.60.7
φ∆
∆ρ /
√ρre
f
η ∆
02
4
-2
-1
0
1
2
-0.2-0.1
00.10.20.3
interplay of 1D gaussian on ηηηη and 2D exponential on (η,φη,φη,φη,φ)
symmetry on (η,φη,φη,φη,φ)and large amplitude increase with greater A-A centrality
peripheral
central200 GeV p-p
LS: like-sign pairs US: unlike-sign pairs
φ∆∆∆∆
soft
hard
0.15 < pt < 2 GeV/cSTAR preliminary
peripheral
central
gaussian to exponential - opaque medium
correlation attenuation by rescattering: exponential peak
1D
2D
STAR preliminary
Au
Au
I f Au+Au collisions weresimply a superposition ofindependent p-p collisions, then we would expect to see one-dimensionalcharge-orderingon ηηηη
but what weobserve is…
a system withtwo-dimensional
charge-ordering on η,φη,φη,φη,φ, implying that the 1D
color strings have “ melted” to form a 2(+)D colored medium
Au
Au
+-+
+++
- --- -
-
-
+
+
-+
+
Au
Au
+-+
+++
- --- -
-
-
+
+
-+
+
φ∆
∆ρ /
√ρre
f
η ∆
02
4
-2
-1
0
1
2
-0.2-0.1
00.10.20.3
STAR preliminary
p-p
ν
−SN
A
exponential
gaussianp-p
ν
σ η, t
an-1
σ φ
ση,pp
tan-1σφ,pp
ση
tan-1σφ
0
2
4
6
8
10
1 2 3 4 5 6
0.4
0.6
0.8
1
1.2
1.4
1.6
1 2 3 4 5 6
A1
A2
A1: 2D exponential –large amplitude dominatescentral Au-Au collisionsA2: 1D gaussian –small amplitude disappears in central collisions
hadronization geometry: 1D for longitudinal string fragments →→→→ 2D for A-A bulk medium
exponential form suggests hadron attenuation in an opaque medium
hadronization geometry
⊗
(b)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.1-0.05
00.050.1
0.150.2
x 10-2
ΣΣΣΣ
∆∆∆∆(d)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.0020
0.0020.0040.0060.0080.01
0.0120.014
~ 4x p-p 80-90% ~ p-p
0-5%
45-55%
20-30%
STAR preliminary
peripheral
central
recoil
Au-Au collisions
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
η ∆
φ∆
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
-0.003-0.002-0.001
00.0010.0020.0030.0040.0050.006
-2
-1
0
1
2
02
4
-0.01-0.008-0.006-0.004-0.002
00.0020.0040.006
⊗⊗⊗⊗blue shift
red shift η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
-0.00250
0.00250.005
0.00750.01
0.01250.015
low-x partons
parton fragments
pt autocorrelation
recoil2q
1qSTAR preliminary
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
0.010.0120.0140.0160.0180.02 p-p
Au-Au
bulk medium
• Medium response to minimum-bias parton stopping
• Momentum transfer to medium
• Velocity structure of medium• Medium recoil observed via
same-side pt correlations
ν
B1,
B2,
B3
(GeV
/c)2
B1−B2 B3
ν
σ η1, σ
φ1
ση1
σφ1
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
1 2 3 4 5 60.4
0.45
0.5
0.55
0.6
0.65
0.7
0.75
0.8
1 2 3 4 5 6
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
η ∆
φ∆
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
00.00250.005
0.00750.01
0.01250.015
0.01750.02
-2
-1
0
1
2
02
4
-0.003-0.002-0.001
00.0010.0020.0030.0040.0050.006
-2
-1
0
1
2
02
4
-0.01-0.008-0.006-0.004-0.002
00.0020.0040.006
20-30%
data −−−− model peak
recoil
fit residuals
fitdatamodel peak
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
00.0020.0040.0060.008
0.010.012
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
00.0020.0040.0060.008
0.010.012
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
00.0020.0040.0060.008
0.010.012 0-10%
0-10%
70-80%
quenchoff
quenchon
Hijingcentrality
STAR preliminary
δη
∆σ2 pt
:n (G
eV/c
)2
δφ 00.5
11.5
2
02
46
00.005
0.010.015
0.020.025
0.030.035
0.040.045
• Minijets: velocity/temperature correlation structures on (η,φη,φη,φη,φ)
• Strong elongation on ηηηη and new negative same-side structure
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
00.0020.0040.0060.008
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
-0.00250
0.00250.005
0.00750.01
0.01250.015
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
-0.0010
0.0010.0020.0030.0040.0050.0060.007
ηηηη∆∆∆∆φφφφ∆∆∆∆
70-80%
20-30%
0-5%
fluctuation scale dependence
η ∆
∆ρ /
√ρre
f (G
eV/c
)2
φ∆-2
-1
0
1
2
02
4
-0.01-0.005
00.0050.01
0.0150.02
0.0250.03
0.035
fluctuationinversion
subtract multipoles
autocorrelation
STAR preliminary
centrality
partons and velocity correlations
vx
vy
x
y
-0.2
-0.1
0
0.1
0.2
-0.25 0 0.25 0.5 0.75 1-0.2
-0.1
0
0.1
0.2
0 0.2 0.4 0.6 0.8 1
1( ) ( ) ( ) ( )stoch mcsv t v t a t a t
τ= − + +� � � ��
Brownian probe in dissipative medium:observable, yet sensitive to medium structure
velocity/temp distr ibut ion β(η,φ)β(η,φ)β(η,φ)β(η,φ)
φ
ηlocal parent
β2β1
2 201/ /n βσ β≡ �(� ,� )
δT
δv
pttp
1D Lévy
( , )tp β η φ↔
1/nT00
� �βσ0/(1 / )n
tA m nβ+Lévy distributions 1D ββββ distribution
velocity displacement
two-point β correlations?
classical point particle
local thermal/velocity structure: response to QCD probe dissipation
WMAPCMB survey
���� pt ���� fluctuations
samples
bulk-medium recoil
hadronization geometry
bulk-medium recoil
yt
y t
1
1.5
2
2.5
3
3.5
4
4.5
1 2 3 4 X(pt1)
r
ˆ - 1
X(pt2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.1-0.05
00.05
0.10.15
0.2
x 10-2
(d)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.0020
0.0020.0040.0060.0080.01
0.0120.014
(b)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.1-0.05
00.050.1
0.150.2
x 10-2
‘ peripheral’ central
saddle curvatures: local T fluctuations
p-p
130 GeVAu-Au
saddle
STAR preliminary
β0
β(η1,φ1)β0
βΣβ∆
1/nΣΣΣΣ
1/n∆∆∆∆
1/n0
2D β distribution∆(1/n)x= 1/nx – 1/n0
x 1(m t
)
x2(m
t)
0.20.4
0.60.80.2 0.4 0.6 0.8
10-4
10-3
10-2
10-1
=
x 1(m t
)
x2(m
t)
0.20.4
0.60.80.2 0.4 0.6 0.8
10-4
10-3
10-2
10-1
1/nΣ ,1/n∆
1/n0
2D Lévy: sibling/mixed
saddle curvatures∆(1/n)Σ, ∆(1/n)∆
2: (1/ ) (1/ )
tp n n nσ Σ ∆∆ ∝ −���� pt ���� fluctuations
ΣΣΣΣ
∆∆∆∆
ηηηηφφφφ
ββββ
model
β(η2,φ2)
yt
yt
?
22
]1,0[ ]GeV 4.0/)(exp[1)(
π
π
mpm
mmpX
tt
tt
+=
∈−−−≡
transport from higher to lower pt evolves with Au-Au centrality; saddle shape consistent with local temperature fluctuations
per ipher al centr al
Au-Au 130 GeV J. Adams et al. (STAR), nucl-ex/0408012.
model fit first residual curvatureevolutionreflects T/vstructure ofmedium y
t
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
(d)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.0020
0.0020.0040.0060.0080.01
0.0120.014
(b)
X(pt1)
r
ˆ -
1
X(p
t2 )
0.2 0.4 0.6 0.8
0.20.4
0.60.8
-0.1-0.05
00.05
0.10.15
0.2
x 10-2
130 GeV Au-Au
200 GeV Au-Au
peripheral
centralSTAR preliminary
same-side – US pairsCI
per pair
per particle
• Number cor relations on pt⊗⊗⊗⊗pt, yt⊗⊗⊗⊗yt in Au-Au reveal medium response to parton dissipation
• Str ucture evolves from par ton fragmentation to local temperature var iations (like CMB survey)
• Low-Q2 par tons as Brownian probes
• Temperature/velocity str ucture on (η,φη,φη,φη,φ)
local thermal/velocity structure
yt
∆ρ /
√ρre
f
y t
1
2
3
4
12
34
00.020.040.060.080.10.120.140.160.18
yt
∆ρ /
√ρre
f
y t
1
2
3
4
51
23
45
00.0050.01
0.0150.02
0.0250.03
0.035
dissipation
parton
p-p p-p Au-Au
~RAA
saddle curvatures on pt⊗⊗⊗⊗pt ↔↔↔↔ T/v correlations on (η,φη,φη,φη,φ) saddle curvatures track changing parton dissipation evolution of parton fragmentation with Au-Au centrality
HBTASSS
1D string fragmentation evolves to 2D hadronization
Compare to predictions of strong ‘suppression’ of net-charge fluctuations
Langevin equation
Dynamical properties of the bulk medium are studied with number and pt correlations
Au-Au results inconsistent with p-p superposition
we consider three aspects of bulk-medium dynamics p-p collisions provide a simple CD reference
suppression of net charge results in longi-tudinal and transverse charge ordering
Au-Au 130 GeV
Au-Au collisions reveal dramatic CD changeslarge amplitude increase, change to symmetric angular correlationssuggest change of hadronization geometry to 2D charge ordering
net-charge fluctuations integrate these negatuve autocorrelations Au-Au CD correlations dominated by hadronization of a bulk medium
/ : number of cor-
related pairs per particle
refρ ρ∆
~ 25 / refρ ρ∆
saddle curvatures on pt⊗⊗⊗⊗pt ↔↔↔↔ T/v correlations on (η,φη,φη,φη,φ) pt autocorrelations from fluctuation scale dependence strong variation of amplitudes and widths with centrality
red shift: particle production from a recoiling source evolution of negative correlation follows same-side peak
what is the local velocity structure of the QCD medium?
first observation of two-particle fragment distributions in Au-Auconnect parton dissipation and local thermal fluctuations
centrality
amplitudes widths
integral is ����pt���� fluctuations
centrality
curvatures
Hijing fails to describe structure, slowly-varying with centralityamplitudes widths subtract same-side model peak to
reveal negative structure beneath→→→→ red shift of local pt spectra
inversion of �pt� fluctuations →→→→ velocity structure resulting from low-Q2 partons
gaussian form
dramaticwidth reduction
