jet discovery of jet quenching and beyond xin-nian wang lbnl, june 29, 05
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Jet
Discovery of Jet Quenching and Beyond
Xin-Nian WangLBNL, June 29, 05
Discovery of Jet Quenching and Beyond
• Introduction: A brief history
• Jet quenching pattern and implications
• Beyond the discovery of jet quenching
Xin-Nian Wang (LBNL)
Shanghai, June 28-29, 2005
The 59th Eastern Forum on Science and Technology
Jet Tomography
41( ) (0) ( )
4iq x em emW q d xe A j j x A
12
22 2
( )
1 ( )
DIS B
B
q qW g F x
q
p q p qp q p q F x
p q q q
qp
qxB
2
2
Dynamic System: Photon or dilepton emission
J/ suppression
( ) ( )emj x j x QCD Response: Quark scattering
A Chronicle of Jet Quenching
• 1982, Bjorken (unpublished): elastic dE/dx too small• 1990,Gyulassy, Pluemer: Evoking inelastic dE/dx• 1992, Gyulassy, XNW: Suppression of leading hadrons
due to jet quenching• 1994, Gyulassy, XNW: First calculation of radiative
parton energy loss with LPM• 1995, Gyulassy, Pluemer, XNW: Estimate of mono-jet rate
in AA at RHIC• 1996, Huang, Sarcevic, XNW: Medium modified
fragmentation function & gamma tagged jet quenching• 1996, Zakharov: Path integral formulation of dE/dx• 1997, Baier et al: non-abelian LPM in QCD- interaction
with gluonic clouds
A Chronicle- Con’ d
• 2000, XNW: First estimate of Cronin at RHIC• 2000, Gyulassy, Levai, Vitev: Opacity expansion I.• 2001, Wiedemann: Opacity expansion II• 2001, Guo, XNW: Higher-Twist expansion and
calculation of modified frag. function.• 2001, XNW, GVW: high pT v2 due to jet quenching • 2002: Suppression of high pT hadron in Au+Au• 2003: v2 at high pt observed • 2003: Suppression of back-side jet• 2003, June 18: d+Au results announced• 2004, azimuthal dependence of away-side jet• 2005, angular correlations within jets
Jet Quenching
• Jet Quenching – Suppression of high pT jet in dense medium
• Experimentally: – Medium modification of jet fragmentation
function (FF)– Suppression of the leading hadrons in FF
• Theoretically: – Parton energy loss before hadronization – Or absorption of leading hadrons from jets
Single Spectra Suppression
Gluon Shadowing and Jet Quenching in A+A Collisions at \sqrt{s}=200 AGeV
XNW and M. GyulassyPhys. Rev. Lett. 68, 1480 (1992)
ET
Away-side suppression or Mono-jet
Azimuthal Anisotropy
Jet Quenching and Azimuthal Anisotropy of Large pT Spectra in Non-central High-energy Heavy-ion Collisions
Phys. Rev. C 63, 054902 (2001) XNW
Non-suppression in p+A
Systematic study of high p(T) hadron spectra in p p, p A and A A collisions from SPS to RHIC energies
Phys. Rev. C 61, 064910 (2000) hep-ph/9812021, XNW
Experimental Evidence
Modified Fragmentation Function
2 ( , )21( , ) (virtual)
(1 ) ( )
Aqg LA S
L Ac q
T x xCzz x
z N f x
Modified splitting functions
2 2 2( , ) ( , ) ( , )h h hD z Q D z Q D z Q
2 122
40
( , ) ( , )2
h
Q
S hq h h L q h
z
zd dzD z Q z x D
z z
Guo & XNW’00
e-
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
Two-parton correlation:
0
320( )(
2ln)a
R
A s
EE C C d
BDPMGyulassy Vitev LevaiWang & WangWiedemann; Zakharov
2( , )~ 1 cos
( )( )
Aqg L
gAq f
T x
f
ydy y
x
x
Quark energy loss = energy carried by radiated gluon
Single spectra in A+A collisions
0
0
0
1 0 0
( , , ) ( , , )L
d
dEE b r d b r n
dx
0 0( , , ) ( , )partb r n b r
ParticipantDensity
2 2 2 2 21 2 1 22
( ) ( )ABA B a a b b
abcdT
dK d b d rd r t r t r dx d k dx d k
dyd p
/ 1 // 2( , , )1
( )( , , ) ab cda A a a b B b b h c c
c
df x k r f x k r
dD z
zt
Single spectra
/ /2 2
( , ) ( , )h c c c h d d d
c d
D z E D z E
z z
Dihadron spectra
Nuclear Modification Factor
NNAB
ABAB
NR
binary
)(2 bbTdN ABbin
Initial state effect: Shadowing & pt broadening: XNW, PRC61(00)064910
Fai, Papp, and Levai (02)
Vitev & Gyulassy (02)
Vitev (03)
Color dipole model
Kopeliovich et al (02)
Alberto Accardi (01)
Wang&Wang2001
Single hadron suppression
Suppression of away-side jet
cE
dE
Azimuthal Anisotropy
Single hadron
Intermediate pT: effects of parton coalescence
Partonic Energy Loss at RHIC
00( , ) ( ) ( )r r R r
E=10 GeV0
13.8 3.9 GeV/fmdE
dx
cold matter
0.5 GeV/fmdE
dx
0 0.2 fm/c
Gyulassy & Vitev;Barnafoldi et alMullerJeon et al
30
1150
40 /fm
gdN
dy
Enke Wang & XNW’2000
Beyond the discovery I: Energy Dependence of quenching
D. d’Enterria, Hard Probes 2004
63 GeV
Effect of non-Abelian energy loss
Eg=Eq
Eg=2Eq
Qun Wang & XNW ‘04
Beyond the Discovery II
dihadron
20-60%
STAR preliminary
20-60%
Azimuthal Mapping of jet quenching
Beyond the discovery III: Measuring Parton Energy Loss
ET
pTtrig
STA
R p
relim
inar
y
STA
R p
relim
inar
y
Beyond the discovery V: Mod. FF
Beyond the discovery IV: Abnormal angular distribution
Summary
• Discovery of Jet Quenching proves that dense matter is formed
• Jet quenching is caused by partonic energy loss• Dense matter at RHIC is 30 times higher than
cold nuclei• The matter is strongly interactive• Jet tomography become useful and power tool
for studying properties of dense matter
Theoretical work in China
• Enke Wang, Benwei Zhang, Hanzhong Zhang, W.C. Xiang etc (IOPP, Wuhan)
• S.Y. Li, Z.G. Shi (Shandong Univ.)
• Qun Wang (USTC)
Collaboration with experimental groups
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