Post on 15-Jan-2016
7th Workshop on QCD and RHIC Physics
Xin-Nian WangLawrence Berkeley National Laboratory
Hard Probes at RHIC: a Theoretical Overview
Hefei, July 9-13, 2008
7th National Workshop on QCD and Relativistic Heavy-ion Collision Physics
Workshop on QCD and RHIC Physics, Wuhan, 2002
First meeting in 2001, CCAST, Beijing
Learning & exchange of ideas
Fun & friendship
New Discoveries
What has happened since then
Chinese STAR Collaboration: MPRC project for TOF
Chinese ALICE Collaboration
Major NSFC Project on RHIC Theory and Phenomenology
Empirical Evidence of sQGP at RHIC
Hydro-dynamics calc.
Pedestal&flow subtracted
A “Perfect Liquid” or sQGP?
Liquid, fluid and (strongly coupled) plasma
Characteristic of liquid orgas: pair correlation
Thoma’ 2006Yu, Xu, Liu & Liu, 2008
How small is the /s?
Room for some range of /s
Huovinen’08
C Geiner & Z. Xu’08
q-hat and Shear Viscosity
1
3 trsT
2 22 2 2
ˆ1 4 2
9tr T Ttr cm T
d qdq q
E dq T
33ˆ2
T
s q
Majumder, Muller and XNW’07
Shear viscosity
Jet quenching ˆ( ) q T ˆ( )q E
2ˆ 1 2 / 0.008 0.025q GeV fms
Jet transport in medium
Ap
0 y
Ap
†( , ) ( ) ( ; ) ( ) ( ; ) |y
yW y y iD y g d y F y
L L
Jet Transport Operator
dpgF v
d
Classical correspondence:
…
(2)( , ) (0) (0; ,0 )exp[ ] ( ,0 ) ( )(4
,0 ) kq ixp yA
dyf x k e A y y kW Ay
L
Liang, XNW & Zhou’08
Maximal Two-gluon Correlation
†0
( ,0 ) ( ; ) ( ) ( ; )( ) |y
yW y g d yi y yD F
L L
22 (0) (0; ( )) ( )4
ni yk
n xpdyM e A y y AW y
L
1 2
4/31
2 1
2 2
(0) ( )
(
( ) ( )
() ) ( )qN N A N N
dy d d F F
d x G x
A y A
Af x A
( )( ( )( )0)D y Dd A y A Ayy
2 ( ) ( )( )
2
nnn A
AA N
yW dy N F dy y xF N G x
p
Medium Broadening
2
22
ˆ( , ) exp ( ) ( )4
( ) exp ( )
kq qA N N N
qN
f x k A d q f k
A k qd q f q
2 ˆ( )N Nk d q
Liang, XNW & Zhou’08Majumder & Muller’07Kovner & Wiedemann’01
2
02
4ˆ( ) ) ) |
1( (A N N x
s FN
c
C
Nxq xG
Jet transport parameter
( ) (0, ) ( )2
ixp AN
dxG x e N F F N
p
L
dpgF v
d
Solution of diffusion eq.
Jet transport parameter & Saturation
Gluon saturation2
2 202
4ˆ ( ) ( , ) |
1s A
A A sat A A N N sat xc
Cq L Q L xG x Q
N
Kochegov & Mueller’98McLerran & Venugapolan’95
2
2
4ˆ ( , ) )
1( ( )A N N
s FF N
c
Cq x
NxG x
Multi-gluon correlation:2 2ˆ( ) ( , )Nq Q xG x Q
Casalderrey-Salana, &XNW’07
q̂̂q
2sQ
DGLAP
Measuring qhat
Direct measurement:
or modified fragmentation function
Measuring parton energy loss
GW:Gyulassy & XNW’04BDMPS’96LCPI:Zakharov’96GLV: Gyulassy, Levai & Vitev’01ASW: Wiedemann’00HT: Guo & XNW’00AMY: Arnold, Moore & Yaffe’03
q
Apxp
xp
Ap
q
x1p+kT
Hadron suppression & medium properties
Bass et al’08
20 0ˆ 1 5 GeV /q fm
2ˆ 0.01 GeV /Nq fmCold nuclear matter in DIS
Wang & XNW’01
Majumder, Wang & XNW’07
OWWZ: Owen, Wang, XNW & Zhang’08
Gamma-jet: toward a true tomography
Isolated photons as tags:
HSW’96, OWWZ’08
Huang, Sarcevic & XNW’96
Volume emission for small zT Surface emission for large zT>1
Jet Quenching phenomenology
2 -fit to single hadron Raa in Au+Au at all centralities at RHIC energy
0
0
0
1 0 0
( , , )L
qd
g b rE ndE
ddL
Phenix’08, see Nagle’s talkOWWZ’08
TECHQM
Theoretical improvements
2
9 (3)ln
2 11rad c
sel
E N ELLT
E
Elastic vs radiative: for finite E & L Qin, et al ‘’08
22
2
ˆ ˆ ˆ( ) ( ,0) ( , ) 2 ( ,0 ( ))gL L
dNc x q q x q
d d Qz
O
Recoil in radiative process:
2
2( )QOQuark-annihilation
Flavor changing process
q
Ap Ap
qNLO corrections to LO collinearfactorized contribution
Mass correction for heavy quarks2
2( )QM
QO
Heavy Quarks
Eel for heavy quark is larger than light quarks
D
dpp
dt
Langevin Eq. for v<<1 Moore & Teaney’05
22 logD s
D
T T
M
pQCD
2
2D
T
M
Strong coupling SYM
Casalderrey-Solana & Teaney’06Gubser’06, Herzog et al’06
Rcb Ratio
Horowitz & Gyulassy’08
Wicks et al’06,Djordjevic et al’06
Armesto, et al’08
Inclusion of multiple gluon emission
2 22
( , ) gdNP z
dzd
Modified DGLAP Evolution Eq. Guo & XNW’00q
Ap Ap
q
22 2
2
( , )( ) ( , ) ( , )
log 2sD z Q dy y
P y P y Q D Qd Q y z
Renk’08
Effects of hydrodynamics
0ˆ( , )E d q r n
0r
n
1D vs. 2+1D
Faster decrease in but increased duration
Gyulassy, et al’02
Viscous hydro, 3-D haydro: effects are expected to be small
Some decrease in anisotropy of E in 1+2D without effect of flow
Gyulassy, et al’02
00
ˆ ˆu p
q qp
Effect of flow
ˆ0.9
ˆflow
no flow
q
q
Baier, Mueller &Schiff’06
Liu, Rajagopal & Wiedemann’06
Azimuthal anisotropy
234.6partN 166.6partN
114.2partN 74.4partN
45.5partN 25.7partN
GeVpT 85
OWWZ’ 2008 Bass et al’08
20-30%
1+1D Bjorken1+2D hydro
Medium response to jets
Sonic mach cones induced by propagating jetsStocker’05, Casaderrey-Solana, Shuryak & Teaney’05 c
cos sc
c
v Mach cone angle:
Sound attenuation with of the cone structure:sT
Neufeld, Muller & Ruppert’08
pQCD/s=1/4
Chesler & Yaffe;07Fries et al’07
SYM
Cone & ridge in parton cascade
Double peak structure was seen in AMPT simulation Ma, et al ‘06
pT=0~1GeV/c
Soft hadrons associated with a jet Minimum distance required
Ridge along tangential jetspunch-through jets
tangential jets
Longitudinal flow (Armesto et al’05)Longitudinal field (Majumder et al’07)Recombination (Hwa’05, Wong’ 07)
Summary
• sQGP still needs to be quantified• Jet transverse momentum broadening provides a
lot of information about the medium: gluon density, gluon correlations, etc, all characterized by jet transport parameter qhat
• Jet quenching provided an indirect measurement of qhat
• Jet quenching phenomenology has advanced to more quantitative analysis
• More exclusive studies such as gamma-jet and medium excitation are necessary