Hirschegg 2012
Xin-Nian Wang
CCNU & LBNL
Jet Propagation in Medium
January 15-21 2012
1
Facets of Strong-Interaction Physics
Thursday, January 26, 2012
Jets in high-energy reactions
2
Thursday, January 26, 2012
Jets in pp collisions at LHC
3
Thursday, January 26, 2012
Jets in Heavy-ion Collisions
4
Thursday, January 26, 2012
Hard Probes of Dense Matter
Jet quenching
kT broadening
Thursday, January 26, 2012
fqA(x) =
�dy−
4πeixp+y−�A|ψ̄(0)γ+ψ(y−)|A�
Deeply Inelastic Scattering
6
k=xpp
Quark distribution in collinear factorized pQCD parton model:
quarks carrying momentum fraction x of the nucleon (nucleus)
Thursday, January 26, 2012
fqA(x) =
�dy−
4πeixp+y−�A|ψ̄(0)γ+L�(0, y−;�0⊥)ψ(y−)|A�
L�(0, y−;�0⊥) = P exp
�ig
� y−
0dξ−A+(ξ−,�0⊥)
�
Gauge Invariance and Multiple Interaction
7
kp
....
Thursday, January 26, 2012
fqA(x,�k⊥) =
�dy−
4π
d2y⊥(2π)2
eixp+y−−i�k⊥·�y⊥�A|ψ̄(0)γ+L(0, y)ψ(y)|A�
L⊥(∞; �y⊥,�0) = P exp
�−ig
� �y⊥
�0⊥
d�ξ⊥ · �A⊥(∞, �ξ⊥)
�
L(0, y) = L†�(∞, 0;�0⊥) L�(∞, y−; �y⊥)L†
⊥(∞; �y⊥,�0⊥)
TMD parton distribution in DISBelitsky, Ji and Yuan (2002)
L�(0, y−;�0⊥) = P exp
�ig
� y−
0dξ−A+(ξ−,�0⊥)
�
kp
....
Thursday, January 26, 2012
Jet Transport in Medium
Classical Lorentz force:
....
fqA(x,�k⊥) =
�dy−
4πeixp+y−�A|ψ̄(0)γ+ exp[ �W⊥(y−) · ∇k⊥ ]ψ(y−)|A�δ(2)(�k⊥)
�W⊥(y−, �y⊥) ≡ i �D⊥(y) + g
� y−
−∞dξ− �F+⊥(ξ−, y⊥)
Liang, XNW & Zhou (2008)
Jet Transport Operator
k
Thursday, January 26, 2012
fqA(x,�k⊥) ≈ A
π∆
�d2q⊥ exp
�− (�k⊥ − �q⊥)2
∆
�fq
N (x, �q⊥)
Momentum Broadening
2-gluon correlation approximation
Thursday, January 26, 2012
fqA(x,�k⊥) ≈ A
π∆
�d2q⊥ exp
�− (�k⊥ − �q⊥)2
∆
�fq
N (x, �q⊥)
Momentum Broadening
∆ = �∆k2⊥� =
�dξ−N q̂(ξN )
Jet transport parameter
Liang, XNW & Zhou’08Majumder & Muller’07Kovner & Wiedemann’01BDMPS’96
Thursday, January 26, 2012
fq A(x
,kT)/
Af
q N(x
,kT)
kT
fqN (x, kT ) ∼ 1/(k2
T + p20)
α
PT Broadening
11
1
Thursday, January 26, 2012
Jet Acoplanarity
12
p+p, s1/2=200 GeV
ET= 10 GeV
ET= 15 GeV
ET (GeV)
g pp(E
T,E T)
(1/G
eV)
0
0.05
0.1
0.15
0 5 10 15 20 25
0
0.05
0.1
0.15
0 5 10 15 20 25
EγT
Thursday, January 26, 2012
∆γ(z, �2⊥) = CA1 + z2
(1− z)+2�4⊥
�dξ−q̂(ξ)[1− cos(xLp+ξ−)]
∆E
E= CA
αs
2π
�dl2Tl4T
�dz[1 + (1− z)2]
�dξ−q̂(ξ)4 sin2(xLp+ξ−/2)
Parton Energy Loss
Splitting functions in medium
kp
....
Parton Energy Loss
Thursday, January 26, 2012
R =NeA
h
NeDh
q̂N ≈ 0.02 GeV2/fm
DIS of large nuclei
14
RMh
Ne
Kr(-0.05)
Xe(-0.2)
+
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8
q̂=0.016 GeV2/fmq̂=0.024 GeV2/fmq̂=0.032 GeV2/fm
z
<E>=10.742 18.358 GeV<Q2>=2.252 GeV2 2.655 GeV2
-
0.0 0.2 0.4 0.6 0.8
RMh
+
6 9 12 15 18 21
<z>=0.326 0.583<Q2>=1.889 2.595 GeV20.2
0.4
0.6
0.8
1.0
E (GeV)
NeKr
(-0.05)
Xe(-0.2)
-
6 9 12 15 18 21 24
q̂=0.016 GeV2/fmq̂=0.024 GeV2/fmq̂=0.032 GeV2/fm
Deng & XNW (2010)
Thursday, January 26, 2012
Drell-Yan in pA Collisions
15
P
A
P
A
P
A
Xing & XNW arXiv:1110.1903 q̂N ≈ 0.02 GeV2/fm
Thursday, January 26, 2012
Jet Quenching phenomena at RHIC
Pedestal&flow subtracted
STAR Preliminary
Thursday, January 26, 2012
Jet quenching in QGP & hadronic phase
17
T [GeV]0.1 0.15 0.2 0.25 0.3 0.35
3/Tq
0
1
2
3
4
5
6
/fm2GeV+0.05-0.04=0.9
0q
30% quenching from hadronic phase
q̂N = 0.02 GeV2/fm
Chen, Greiner, Wang, XNW, Xu (2010)
Thursday, January 26, 2012
Survival under the LHC sea
18
q̂ ∝ 1τ0πR2
A
dNch
dη
Thursday, January 26, 2012
Jet Quenching at LHC
19
Thursday, January 26, 2012
ω > ωc
ωc = 1− 2 GeV
Di-Jet Asymmetry
20Y. He, Vite, B.W. Zhang, arXiv:1105.2566
Thursday, January 26, 2012
Mach-cone-like excitation
21
Thursday, January 26, 2012
gamma-hadron correlation
22
Guo-liang Ma & XNW (2011)
Thursday, January 26, 2012
Summary
• Jet propagation in medium leads to pt broadening and parton energy loss
• Jet transport in medium can be studied through pt broadening and jet quenching
• Jet quenching in heavy-ion collisions shows large jet transport parameter
• Jet quenching also leads to medium excitation that can be measured via correlation
23
Thursday, January 26, 2012
Theoretical uncertainties
24
N. Armesto et al. arXiv:1106.1106Systematic comparisons of different approaches:
Single gluon emission
Sensitivity to maximumangle cut-off for gluonemission
Thursday, January 26, 2012
collinear k2⊥ < µ2
large angle k2⊥ > µ2
Collinear approximation & NLO pQCD
25
.... ksingle jet -- LO
.... k
two jets -- NLO
Thursday, January 26, 2012
Future Perspectives
26
Thursday, January 26, 2012
Top Related