Transcript Folie 1

Charmonium dynamics in heavy ion collisions
Olena Linnyk
28 June 2007
Charmonium production vs absorption
Initial State
D
J/Y
Hadronization
time
Y‘
cC
Dbar
Freeze-out
Quark-Gluon-Plasma ?
Transport models
Microscopical transport models provide the dynamical
description of nonequilibrium effects in heavy-ion collisions
Basic concepts of Hadron-String Dynamics
• for each particle species i (i = N, R, Y, p, r, K, …) the phase-space density f
i
follows the transport equations



 
  pH r - rH


t






 f i ( r , p ,t)  I coll (f 1 ,f 2 ,...,f M )
p

with the collision terms Icoll describing:
elastic and inelastic hadronic reactions BB <-> B´B´, BB <-> B´B´m, mB <-> m´B´, mB <-> B´
formation and decay of baryonic and mesonic resonances
string formation and decay (for inclusive production: BB->X, mB->X, X =many particles)
• Implementation of detailed balance on the level of 1<->2 and 2<->2 reactions
(+ 2<->n multi-meson fusion reactions)
• Off-shell dynamics for short living states
Degrees of freedom in HSD
• hadrons - baryons and mesons including excited states (resonances)
• strings – excited colour singlet states (qq - q) or (q – qbar)
•
Based on the LUND string model
& perturbative QCD via PYTHIA
leading quarks (q, qbar) & diquarks
(q-q, qbar-qbar)
pre
time
-ha
dro
ns
pr
ro
ad
h
e
ns
__
q
F
qq
color electric
field
z
NOT included in the transport models presented here :
o no explicit parton-parton interactions (i.e. between quarks and gluons) outside
strings!
o no QCD EoS for partonic phase
under construction:
PHSD – Parton-Hadron-String-Dynamics W. Cassing arXiv:0704.1410
Charmonium production

Hard probe -> binary scaling!
Charmonium production in pN
7
10
6
10
60
D+Dbar
p+N
1/2
pp->J/Y+X, s =200 GeV
4
10
J/Y
3
10
Y/
102
Br ds/dy [nb]
s(s) [nb]
105
40
20
1
10
100
0
10-1
10
1/2
s [GeV]
100
-4
-2
0
2
PHENIX
HSD scaled with cross section ratio
sJ/Yexp = sJ/Y + B(cc->J/Y) scc + B(Y‘->J/Y) sY‘
4
Regeneration
At SPS recreation of J/Y by D-Dbar annihilation is negligible
10
-3
10
-1
1/2
Pb+Pb, s =17.3 GeV, central
10
-6
dN/dt
10
-5
10
-7
10
-8
J/Y+m->D+Dbar
D+Dbar->J/Y+m
10
-2
10
-3
10
-4
J/Y+m->D+Dbar
D+Dbar->J/Y+m
dN/dt
10
1/2
Au+Au, s =200 GeV, central
-4
5
10
time [fm/c]
15
20
5
10
15
20
time [fm/c]
But at RHIC recreation of J/Y by D-Dbar annihilation is strong!
Charmonium absorption
Charmonium is absorbed by :



Scattering on nucleons (normal nuclear absorption, as in pA)
Interaction with secondary hadrons (comovers)
Dissociation in the deconfined medium (suppression in QGP)
Normal absorption
40
Pb+Pb, 158 A GeV
In+In, 158 A GeV
30
20
10
0
0
100
200
300
.
HSD
Baryon absorption
Glauber model
NA50 2004
400
0
Baryon absorption
Glauber model
NA60 2005
HSD
50
Npart
NA50 (QM2002):
Anomalous absorption of J/Y in very central Pb+Pb
100
150
200
Npart
=
Discovery of QGP !?
Scenarios for anomalous charmonium suppression
• QGP colour screening
• Comover absorption
[Matsui and Satz ’86]
[Gavin & Vogt, Capella et al.`97]:
cC melting
J/Y
Digal, Fortunato, Satz
hep-ph/0310354
but (!)
 Lattice QCD predicts (2004): J/Y can
exist up to ~2 TC !
 Regeneration of J/Y in QGP at TC
[Braun-Munzinger, Thews, Ko et al. `01]
J/Y+g <-> c+cbar+g
charmonium absorption by low
energy inelastic scattering with
‚comoving‘ mesons (m=p,h,r,...
J/Y+m -> D+Dbar
Y´ +m -> D+Dbar
cC +m -> D+Dbar
but (!)
 Comover density and meson
absorption cross sections unknown
 Regeneration (D+Dbar->J/Y+m)
Scenarios for anomalous charmonium suppression
in HSD
• QGP colour
screening
Threshold
melting
[Matsui and Glauber
Satz ’86]model [Blaizot et al.]
= geometrical
cC melting
Charmonia suppression sets in abruptly at
J/Y
threshold energy densities, where
cc is melting,
Digal, Fortunato, Satz
Y´ is melting, hep-ph/0310354
J/Y is melting
• Comover
absorption
Comover
absorption
Phase-space
model
cc+meson
dissociation
[Gavin &
Vogt, for
Capella
et al.`97]:
charmonium absorption by low
energy inelastic scattering with
‚comoving‘ mesons (m=p,h,r,...
J/Y+m -> D+Dbar
10
J/Y+r Y´ +m -> D+Dbar
D+Dbar, D+Dbar
10
c
+m
->
D+Dbar
C
J/Y+K
1
*
*
1
s [mb]
s [mb]
*
J/Y+p
but (!)
butJ/Y+K(!)
10
D+Dbar
 Lattice QCD predicts (2004): J/Y can
D +Dbar
 Comover density and meson
exist
up to ~2 TC !
absorption cross sections unknown
Lattice
QCD:
10
10
Regeneration
of J/Y in QGP at TC
3
4.0
4.5
5.0
5.5
 4.0 Regeneration
(D+Dbar->J/Y+m)
e(c
)
=2
GeV/fm
4.5
5.0
5.5
c
s [GeV]
[Braun-Munzinger,
Thews, Ko et al. `01]
s [GeV]
e(Y´) =2
GeV/fm3
3 c+cbar+g
J/Y+g
<->
Inverse cross sections by detailed balance!
e(J/Y)=16
GeV/fm
0
*
-1
0
1/2
1/2
*
Comparison to data
NA60, In+In, 158 A GeV
QGP threshold melting
NA50, Pb+Pb, 158 A GeV
QGP threshold melting
1.2
1.0
0.8
0.6
HSD
(s(J/Y)/s(DY)) / (s(J/Y)/s(DY))Glauber
(s(J/Y)/s(DY)) / (s(J/Y)/s(DY))Glauber
Pb+Pb and In+In @ 158 A GeV
J/Y
NA60, In+In, 158 A GeV
Comover absorption
NA50, Pb+Pb, 158 A GeV
Comover absorption
1.2
1.0
0.8
0.6
HSD
0.4
0.4
0
50
100
150
200
Npart
250
300
350
400
0
50
100
150
200
250
300
350
400
Npart
In+In consistent both with threshold melting and comover absorption
scenarios; Pb+Pb indicates importance of comover interaction
[E.L.Bratkovskaya et al PRC69 (2004) 054903, OL et al NPA786 (2007) 183]
Pb+Pb and In+In @ 158 A GeV
Y´
B(Y') sY' / B(J/Y) sJ/Y
Pb+Pb, 158 A GeV
HSD
0.015
NA50 1997
NA50 1998-2000
Comover absorption
QGP threshold melting:
3
eJ/Y =16, ec =2, eY '=2 GeV/fm
c
0.010
eJ/Y =16, ec =2, eY '=6.55 GeV/fm
3
c
0.005
0.000
0
25
50
75
100
125
150
ET [GeV]
Y´ data contradict threshold melting scenario with lQCD ed
Au+Au @ s1/2=200 GeV
Comover absorption

Au+Au, s=200 GeV,
PHENIX, |y|<0.35
PHENIX, 1.2<|y|<2.2
1.0
RAA(J/Y)
In comover
scenario,
suppression at
mid-y
stronger than at
forward y,
unlike data
comover absorption
Space for parton
phase effects
0.5
D+Dbar<-> J/Y +m
3
+ ecut=1 GeV/fm
D+Dbar<-> J/Y +m
0.0
0.015
B(Y') sY' / B(J/Y) sJ/Y
HSD
|y|<0.35
1.2<|y|<2.2
0.010
0.005
0.000
0
100
200
Npart
300
0
100
200
Npart
300
[OL et al arXiv:0705.4443]
Au+Au @ s1/2=200 GeV
Threshold
melting

Au+Au, s=200 GeV,
without recombination
RAA(J/Y)
1.0
+ recombination
D+Dbar<-> J/Y +m
3
+ ecut=1 GeV/fm
+ recombination
D+Dbar<-> J/Y +m
PHENIX, |y|<0.35
PHENIX, 1.2<|y|<2.2
1.0
0.5
0.5
0.0
0.0
HSD
0.015
B(Y') sY' / B(J/Y) sJ/Y
QGP threshold scenario
0.015
|y|<0.35
1.2<|y|<2.2
0.010
0.010
0.005
0.005
0.000
0.000
0
100
200
Npart
300
0
100
200
Npart
300
0
100
200
300
400
Npart
Neither of the two scenarios describes PHENIX data
J/Y excitation function
Central
1.0
0.8
Comover + eEcut
QGP + eEcut
J/Y excitation function
Minimal bias
1.0
Comover
QGP
0.6
S
S
0.6
0.8
0.4
0.4
0.2
0.2
HSD
0.0
100
1000
Ebeam, A GeV
10000
0.0
100
1000
10000
Ebeam, A GeV
Comover reactions in the hadronic phase give almost a constant suppression;
pre-hadronic reactions lead to a larger recreation of charmonia with Ebeam .
The J/Y melting scenario with hadronic comover recreation shows a maximum
suppression at Ebeam = 1 A TeV; exp. data ?
Y´ excitation function
B(Y ') sY' / B(J/Y) sJ/Y
Central
0.012
Comover+E
e cut
QGP+E
e cut
Y ' to J/Y ratio
Minimal bias
Comover
QGP
0.008
0.004
HSD
0.000
100
1000
Ebeam, A GeV
10000
100
1000
10000
Ebeam, A GeV
Y´ suppression provides independent information
on absorption vs. recreation mechanisms !

J/Y probes early stages of fireball and HSD is the tool to model it.

Comover absorption and threshold melting both reproduce J/Y
survival in Pb+Pb as well as in In+In @ 158 A GeV, while Y´ data
favour comover absorption.

Neither hadronic interactions nor colour screening satisfactory
describes the data @ s1/2=200 GeV for Au+Au.

Deconfined phase is clearly reached at RHIC, but a theory having
the relevant/proper degrees of freedom in this regime is needed
to study its properties (PHSD).
arXiv:0705.4443
nucl-th/0612049
arXiv:0704.1410
Back-up slide 1 FAIR predictions
Au+Au, 25 A GeV
Comover absorption
QGP threshold melting
3
eJ/Y =16, ec =2, eY '=6.55 GeV/fm
QGP threshold melting
3
eJ/Y =16, ec =2, eY '=2 GeV/fm
1.0
S(J/Y)
0.8
B(Y') sY' / B(J/Y) sJ/Y
0.006
c
0.004
0.6
0.4
Baryon absorption
Comover absorption
QGP threshold melting
3
eJ/Y =16, ec =2, eY '=6.55 GeV/fm
0.2
HSD
c
0.0
0
50
100
150
200
Npart
250
c
0.002
HSD
0.000
300
350
400
0
50
100
150
200
Npart
250
300
350
400
Back-up slide 2 Energy density
B dN(J/Y)/dy
Back-up slide 3 Rapidity
10
-3
10
-4
10

Au+Au, s=200 GeV
threshold melting +energy cut
comover absorption +energy cut
QGP no cut
comover no cut
HSD
central
PHENIX
-5
-3
-2
-1
0
y
1
2
3