Heavy quarks and charmonium at RHIC and
LHC within a partonic transport model
Jan Uphoff
with O. Fochler, Z. Xu and C. Greiner
based on arXiv:1003.4200, 1004.4091, 1008.1995 & 1011.6183
XLIX International Winter Meeting on Nuclear Physics
Bormio, 23-29 January 2011
Outline
• Motivation
• Heavy quark processes in BAMPS
• Heavy quark production in heavy-ion collisions
• Elliptic flow and energy loss of heavy quarks
• J/ψ production
• Summary
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
1
Heavy-ion collision at LHC
BAMPS simulation of QGP phase at LHC at sNN = 2.76 TeV
Visualization framework
courtesy MADAI
collaboration, funded by
the NSF under grant# NSFPHY-09-41373
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
2
Motivation
Large heavy quark mass
>> ΛQCD
_
D
D
Charm: Mc ≈ 1.5 GeV
Bottom: Mb ≈ 4.75 GeV
Heavy quark
production at early
_
c
c
stage of collision
Pre-equil. phase
ideal probe for this
stage
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
3
BAMPS
BAMPS: Boltzmann Approach of MultiParton Scatterings
• 3+1 dimensional, fully dynamic parton transport model
• solves the Boltzmann equations for on-shell partons with pQCD interactions
Z. Xu & C. Greiner,
Phys. Rev. C71 (2005)
Phys. Rev. C76 (2007)
Implemented processes:
Light quarks are currently being implemented
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
4
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
QGP
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
5
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
QGP
Hadronic phase
No interactions taken into
account
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
6
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
Initial hard
parton
scatterings
QGP
Hadronic phase
No interactions taken into
account
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
7
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
Initial hard
parton
scatterings
_
c
c
_
c
Energy loss
Charm
production
c
c
_
c
J/ψ
QGP
Hadronic phase
No interactions taken into
account
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
8
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
Initial hard
parton
scatterings
_
c
c
_
c
Energy loss
Charm
production
J/ψ
dissociation
c
_
c
J/ψ
c
J/ψ
regeneration
QGP
c
_
c
J/ψ
Hadronic phase
No interactions taken into
account
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
9
Sketch of heavy-ion collision in BAMPS
Heavy flavor in BAMPS
e
D
Initial hard
parton
scatterings
D
_
c
D
c
_
c
D
J/ψ
dissociation
D
Energy loss
Charm
production
c
_
c
J/ψ
c
J/ψ
regeneration
QGP
c
_
c
J/ψ
D
Hadronic phase
No interactions taken into
account
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
10
Initial conditions
Heavy quarks:

NLO pQCD
Distributions from R. Vogt

PYTHIA
Monte Carlo Event Generator
for nucleon-nucleon collisions
Gluons:
 PYTHIA
scaling to heavy-ion collisions with
Glauber model (considering shadowing)
and energy conservation
 Minijets
(low pT cut-off at 1.4 GeV)
 Color glass condensate
H.J. Drescher & Y. Nara, Phys. Rev. C75
(2007)
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
11
Charm production in the QGP at LHC
charm pairs
BAMPS
LHC
Large secondary production
→ Can even be comparable to
initial production
charm pairs
November run
JU, Fochler, Xu, Greiner
Phys. Rev. C 82 (2010)
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
12
Elliptic flow v2 &
nuclear modification factor RAA
Elliptic flow
Nuclear modifaction factor
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
13
v2 and RAA for gluons
RHIC
O. Fochler, Z. Xu & C. Greiner,
Phys.Rev.Lett.102 (2009)
Z. Xu & C. Greiner,
Phys. Rev. C 79 (2009)
central Au+Au
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
14
Heavy quark elliptic flow v2 at RHIC
 gQ gQ  K  gQ gQ
RHIC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX data,
arXiv:1005.1627
15
Heavy quark elliptic flow v2 at RHIC
 gQ gQ  K  gQ gQ
RHIC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX data,
arXiv:1005.1627
16
Heavy quark scattering
Leading order perturbative QCD:
t channel is divergent for small t
can be fixed to
by comparing dE/dx to
HTL result beyond
logarithmic accuracy
A. Peshier,
arXiv:0801.0595
[hep-ph]
P.B. Gossiaux,
J. Aichelin,
Phys.Rev.C78 (2008)
Introduce a running coupling
constant for all channels
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
17
Heavy quark elliptic flow v2 at RHIC
 gQ gQ  K  gQ gQ
RHIC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX,
arXiv:1005.1627
18
Heavy quark RAA at RHIC
 gQ gQ  K  gQ gQ
RHIC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX,
arXiv:1005.1627
19
Heavy quark elliptic flow v2 at RHIC
 gQ gQ  K  gQ gQ
LHC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX,
arXiv:1005.1627
20
Heavy quark RAA at RHIC
 gQ gQ  K  gQ gQ
LHC
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX,
arXiv:1005.1627
21
J/ψ suppression
Cold nuclear matter effects
Hot nuclear matter effects

 J/psi dissociation
Shadowing
 If T > Td = 2 Tc = 330 MeV
 Via

Cronin effect
 J/psi regeneration
via

Nuclear absorption
Bhanot+Peskin 79
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
22
J/ψ production
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
23
J/ψ production
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
24
J/ψ production
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
25
J/ψ production
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
26
Conclusions & outlook
Full space-time evolution of QGP with charm and bottom quarks and J/
• Small charm yield during QGP phase at RHIC, not necessarily negligible at LHC
• LO gluon heavy quark scattering is not sufficient to build up collective flow and
RAA
• Running coupling and improved Debye screening yield results closer to data
• J/ yield smaller than data
Further details on arXiv:1003.4200, 1004.4091, 1008.1995 & 1011.6183
Future tasks:
• Radiative corrections for heavy quark scattering
• Light quarks
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
27
Thank you for your attention.
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
28
Heavy quark RAA at RHIC
 gQ gQ  K  gQ gQ
only elastic heavy quark processes
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
PHENIX,
arXiv:1005.1627
29
Heavy quark scattering cross section
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
30
Heavy quark elliptic flow v2 at RHIC
When does the elliptic flow build up?
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
31
Initial conditions for cascade at LHC
In agreement with most of LHC predictions
(cf. N. Armesto, J.Phys.G35 (2008)
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
32
Heavy quark scattering
Compare to analytic formula
Introduce a running coupling
constant for all channels
Jan Uphoff
Heavy quarks and charmonium at RHIC and LHC
33