Cold and Hot nuclear matter effects
on Charmonium production
Kai Zhou (Tsinghua University,Beijing)
In collaboration with:
Baoyi Chen (Tsinghua University)
Yunpeng Liu (Frankfurt University)
Nu Xu (CCNU)
Pengfei Zhuang (Tsinghua University)
1
Ø Motivation
Ø Cold & Hot Nuclear Matter Effects
Ø Numerical results at RHIC and LHC
Ø Summary
2
Ø Motivation
Matsui and Satz: PLB178, 416(1986):
J/Psi suppression as a probe of QGP in HIC
color screening ----->
melting of the
bound states ----->
yields suppressed
● quarkonia can survive above Tc,
a sensitive signature of QGP formation
● heavy quarks are produced via hard processes,
rather solid theoretical ground
3
Ø Motivation
extract information about QGP, but many effects should be taken into account:
Interplay of Hot and Cold Nuclear Matter effect:
--- Cold Effects : Shadowing, Nuclear Absorption, Cronin
---
Hot Effects : color screening, recombination
4
Ø Cold & Hot Nuclear Matter Effects
Transport (Hot & Cold) + Hydrodynamic Approach
Transport
Equation
for Jpsi
Hydrodynamic
Evolution for
medium
hot matter
effects
cold matter
effects
5
Ø Cold & Hot Nuclear Matter Effects
Transport :
Hot Nuclear Matter Effects
●the quarkonium distribution function in phase space f ( p, x , t )


 
 
 
  t  t f  , xt , pt     f ( , xt , pt )  
g  J /  c  c


p g u  / T
1 /( e
 1)

1
d k

 g  4 Fg f g (k , x)
3

gluon dissociation cross section by
2mt (2 ) 2 E g
3
Hot
Effects
OPE (Peskin,1999)

3
3
1
d k
d q1
d q2
4 4

(
2

)
 ( p  k  q1  q2 )W pro ( s) f c (k , x) f c (k , x)
3
3
3

2mt (2 ) 2 E g (2 ) 2 Ec (2 ) 2 Ec regeneration by detailed balance !
3
 r  (T )
 g (T )   g (T  0)
2
 r  (T  0)
2
6
from Potential Model
Ø Cold & Hot Nuclear Matter Effects
Transport :
Cold Nuclear Matter Effects
●initial distribution f ( p, x, t0 ) for transport Eq. including Cold Effects
for Jpsi & charm
Shadowing
R. Vogt, Phys. Rev. C 71 (2005) 054902
Cold
Effects
Absorption
Cronin
s NN
e y
pT broadening (Gaussian smearing)
agN   ( )
2
x1g, 2 
at LHC can safly be neglected
mc2c  pT2

inelasitic
pp
0
agN  0.15GeV 2 / c 2 @ LHC Pb-Pb 2.76TeV
7
Init.J.Mod.Phys.E.12,211(2003)
Phys.Rev. C 73, 014904(2006)
Ø Cold & Hot Nuclear Matter Effects
Hydrodynamic :
Background Medium Evolution
● 2+1D hydrodynamics(
B  0 )
 T   0
Longitudinal Bjorken Expansion
● Equation Of State:
Ideal Gas with quarks and gluons for QGP & HRG
● Initial conditions :
Glauber model & constrained by Charged Multiplicities or from well
tested HydroCode
8
Ø Numerical Results
RHIC Au-Au 0.2TeV : Ratio of 1.2<y<2.2 to |y|<0.35
rule out the approach with
only cold matter effects.
shadowing effect is important,
and the total yield is sensitive
to it.
9
Ø Numerical Results
RHIC Au-Au 0.2TeV : Ratio of 1.2<y<2.2 to |y|<0.35
rule out the approach with
only cold matter effects.
transverse momentum is not
so sensitive to shadowing.
10
Ø Numerical Results
LHC Pb-Pb 2.76TeV : Inclusive Jpsi
picked out from talk by E. Scomparin at QM2012( fot the ALICE Collaboration)
11
Ø Numerical Results
LHC Pb-Pb 2.76TeV : 2.5<|y|<4.0 Inclusive Jpsi
the band due to considering or
not considering Shadowing
B-decay contribute~10% totaly
Reg. vs Init.@,most central collisions is larger than 50% : 50%
almost no centrality dependence above Np~100
cc
d NN
dy
12
 0.38mb
2.5 y  4
FONLL
Ø Numerical Results
LHC Pb-Pb 2.76TeV : 0 <|y|<0.9 Inclusive Jpsi
the band due to considering or
not considering Shadowing
B-decay contribute~10% totaly
Reg. vs Init.@,most central collisions is larger than 70% :30%
cc
d NN
dy
13
 0.6mb
2.5 y  4
FONLL
Ø Numerical Results
LHC Pb-Pb 2.76TeV :
Raa(Np) for different pt bins:
14
prediction
Ø Numerical Results
LHC Pb-Pb 2.76TeV :
Raa(Np) for different pt bins:
15
prediction
Ø Numerical Results
LHC Pb-Pb 2.76TeV : 2.5<|y|<4.0 Inclusive Jpsi
data : ALICE 0-90%
low pt region is dominated
by regeneration
Suppression increases with
increasing pt, a valley structure
unvertainties arised from
shadowing effect
picked out from talk by E. Scomparin at QM2012
16
Ø Numerical Results
LHC Pb-Pb 2.76TeV : 2.5<|y|<4.0 Inclusive Jpsi
data : ALICE 0-90%
low pt region is dominated
by regeneration
Suppression increases with
increasing pt, a valley structure
uncertainties arised from
shadowing effect
17
Ø Numerical Results
s NN 
hot
medium
effect
stronger
rAA 
pT2
AA
pT2
pp
1,compared to total yield, not so sensitive to the cold
nuclear matter effects.
2, very sensitive to the degree of heavy quark
thermalization.
18
Ø Numerical Results
s NN 
hot
medium
effect
stronger
rAA 
pT2
AA
pT2
pp
1,compared to total yield, not so sensitive to the cold
nuclear matter effects.
2, very sensitive to the degree of heavy quark
thermalization.
19
Ø Summary
Ø Both the cold and hot nuclear matter effects
are included self-consistently in the transport
approach and the recent data support our
prediction.
Ø While the total yield is sensitive to both the cold
and hot effects,theTransverse Momentum
Dependense is mainly controlled by the hot effect.
Ø we introduce
rAA 
pT2
AA
pT2
pp
which can be used to
probe the QGP formation at RHIC and LHC.
20
Thank You!
21
Input
● medium evolution
RHIC :  0  0.6 fm,  pp  41 mb, T0  344 MeV
LHC :  0  0.6 fm,  pp  62 mb,
T0  430 and 484 MeV for forward and mid rapidity
● initial production
RHIC :  abs  0, agN  0.1 GeV 2 / fm,
 ppJ /  0.42 and 0.74  b for forward and mid rapidity
LHC :  abs  0, agN  0.15 GeV 2 / fm,
 ppJ /  2.33 and 3.5  b for forward and mid rapidity
● regeneration
RHIC :  ccpp  0.04 and 0.12mb for forward and mid rapidity
LHC :  ccpp  0.38 and 0.6 mb for forward and mid rapidity
V=U for Td
22
Charmonium in pp Collisions
pp  ' X

 B( '      )
observation: J / , '    ,
1.5%
pp  J / X
 

 B( J /    )
difficult to observe ψ’ !
Ψ’ and χc decay into J/ψ:


P(  c  J /   ) 30%
Ψ’
P( '  J /  2 ) 10%
direct production 60%
χc
J/ψ
mechanisms for quarkonium production in pp:
it is difficult to describe quarkonium formation due to confinement problem
1) color evaporation model:
color evaporation
gg  colored  cc  
 J /
2) color-singlet model:
gg   cc J /  g
3) color-octet model:
  gg  cc 
n
X

n
n: quantum numbers of color, angular momentum and spin
23