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