Recontres de Moriond, March 17 2005

Xin-Nian WangLawrence Berkeley National Laboratory

High PT Physics at RHIC

QCD phase transition

,1

1( )

2 4

fna

QCD a a af a

L i gA m F F

0

(approx.) Chiral symmetry and its spontaneous breaking:

Goldstone boson and chiral condensate

22 2 23

4( )

(11 ) ln( / )sf QCD

Qn Q

SU(3) gauge symmetry:

Asymptotic freedom

Confinement

412

sa aT F F B

scale anomaly (break scale invariance)

1/ 40.72cT B

Lattice QCD results

MeVTc 8170 3/ 3.06.0 fmGeVc

F. Karsch ‘2001

Medium Response Function

41( ) (0) ( )

4iq x em emW q d xe A j j x A

1

2

2

2 2

( )

( )1

B

B

DIS

q qW g

q

p q p qp q p q

F

xq

Fp q q

x

qp

qxB

2

2

Dynamic System: Photon or dilepton emission (space-like photon)

J/ suppression

( ) ( )emj x j x QCD Response: Strong quark scattering

DIS off Nuclei

e-

, )) (( ,( )qh

q h hHdW

d f x p q Dxd

zz

x

pypedy

xf yixpBq )()0(

2

1

2)(

/( ) 0 (0) , , ( ) 02 2 2

h hip y zhq h h q h h q

S

z dyD z e Tr p S p S y

Frag. Func.

22 )(2)(2

1),,( xpqxpqpTreqpxH q

Twist Expansion

AyyFyFAedydydy

d

d yypixypixsD TB )()()(2

)0(222

~ 21)(21

4221

)()(~ 3/44 TTsBqs xGxxfA

])(1)[(~ 3/12222

TTS

BqsDS xGxAcxAf

d

d

d

d

3/1

22 LPM

A

Q 2

3/2

1Q

Ac

LPM interference Effect

_2 1( )

41 1L Lix p y ix p y yS

T

e e

1f

Lx p

Formation time

2

2 (1 )T

Lx pq z z

[ , , ]Tzq

2 ~ 0x 2 Lx x

Modified Fragmentation

2 122

40

( , ) ( , )2

h

Q

S hq h h L q h

z

zd dzD z Q z x D

z z

2 ( , ) 21( , ) (virtual)

(1 ) ( )

Aqg L A S

L Aq c

T x x Czz x

z f x N

Modified splitting functions

_2 1(

1 2 1 2

2)

1

( , ) (0) ( ) ( ) ( )2 2

( ) ( )1 1

B

L Lix p y ix

ix p yA

y

g

y

q L

pe

dyT x x dy dy e A F y F y y A

y y ye

Two-parton correlation:

LPM

Guo & XNW’00

HERMES data

2 20.00065 GeVsC 0.5 GeV/fmdE

dx

in Au nuclei

E. Wang & XNW2000

Parton Energy Loss

2 1 22

2

2 2 20 0

( ,(1 )

(

1 )

)

Q Aqg L

AA s

gq

TcT T T

Czz

Td dz

N

x x

f xk

0

320( )(

2ln)a

R

A s

EE C C d

BDPMGyulassy Vitev LevaiWang & WangWiedemann; Zakharov

Quark energy loss = energy carried by radiated gluon

2( , )~ 1 cos

( )( )

Aqg L

gAq f

g

ydy

T xy

x

f x

2( ) ~s gxG x

High pt spectra in pp collisions

H. ZhangJ. OwensE. WangXNW2005

High pt spectra in Au+Au

( ) ( )D z D z

H. Zhang,E. WangJ. Owens, XNW 2005

0

( )

Jet Quenching at RHIC

XNW’03

NNAB

ABAB

NR

binary

Geometry of dense matter

Non-central collisions

Azimuthal asymmetry

0 1 2(1 cos 2 cos 2 )chdNN v v

d

jet

jet

No suppression in d+Au

STAR PHENIX

pT spectra at large rapidity

Catalin Ristea (BRHAMS)

Greg Rakness (STAR)

Edmond Iancu (Theory)

Gluon saturation or color glass condensate ?

Energy Dependence of quenching

D. d’Enterria, Hard Probes 2004

0 20

1( ) ch

gA

dN

R dy

Effect of non-Abelian energy loss

Eg=Eq

Eg=2Eq

Qun Wang & XNW nucl-th/0410079

EskolaHonkanenSalgadoWiedemann

Fixed pT=6 GeV

Dihadron Correlation

pTtrig=4-6 GeV

pT=2-4 GeV

Pedestal&flow subtracted

Pedestal&flow subtracted

trigger

Away-side suppression

0

13.8 3.9 GeV/fmdE

dx

cold matter

0.5 GeV/fmdE

dx

Modification of the dihadron distribution

Pedestal&flow subtracted

STAR preliminary

Effect of longitudinal flow

C. Salgado

z

Jet Remnants

STARPHENIX

Angular distribution of radiative gluons

2

2 2

1 (1 ) 1

2g S

FT T

dN zC

dzdk z k

1gdN

d

max

(1 / )

2g

g

E

R

Radiation in vacuum

2

2 (1 )f

T

Ez z

k

22 2

2 2 2 2

1 (1 ) 11

( )f

R

g A S

T c T T

dN C zcmR e

dzdk N z k k

Induced Bremsstrahlung:

Further interaction of the radiated gluons with the medium?

Sonic Boom

cos M sc

M Trigger

Casalderrey-Solana, Shuryak and Teaney

Linearize disturbance

Summary

• Large suppression of high pT spectra

• Strong medium modification of jet structure

• 30 times higher gluon density than cold nuclei

Bulk Elliptic Flow

)2cos2cos1( 210

vvNd

dNch

Hydro-dynamics calc.

2cos2 v

Pressure gradient anisotropy

Summary

• Large suppression of high pT spectra• Strong medium modification of jet structure• 30 times higher gluon density than cold nuclei• Strongly interacting quark-gluon plasma• Beginning of jet tomography study

– Details of modified fragmentation– Heavy quark fragmentation (R. Averbeck)– Dihadron fragmentation– Jet-gamma events

Di-hadron fragmentation function

1 2 1 2 1 2 1 2( , ) 0 (0) , , ( ) 02q h h q h h h h q

S

D z z Tr p p S p p S y

h1 h2

jet

Majumder

Future of Jet quenching

STA

R p

relim

inar

y

STA

R p

relim

inar

y

+jet correlation in Au+Au in run4?

More accurate determination of initial Et

Modification for Heavy Quarks

2

1

1/ (1 ) / 2Hf

f z M zq

(1) Slow clock for formation time

Djordjevic & GyulassyZhang & XNWArmesto,Dainese, Salgado & Wiedemann

(2) Color factor

(3) Dead cone effectEQ<Eg, Eq

Zhang & XNW

Charm quark

Large charm quarkSuppression?

Hadronic scattering?

Parton recombination

Hwa; Fries

Particle or parton correlations are not trivial