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					                                                HENP


J/Ψ Transport in QGP and Pt Distribution             at
                  SPS and RHIC
               Xianglei Zhu, Pengfei Zhuang
                     (Tsinghua Univ.)
                           Nu Xu
                          (LBNL)

        Motivation
        J/Ψ transport in QGP
        QGP evolution
        J/Ψ Pt distribution and elliptic flow
        Conclusions

  2004-8-16             ICHEP04   Beijing        1
                                                HENP

                   Motivation
J/Ψ suppression: an important signature of QGP
Normal suppression: nuclear absorption
Anomalous suppression: due to QGP or comovers
Questions:
1)J/Ψ production mechanism at RHIC: initial gluon
fusion or coalescence at hadronization?
2) Almost all models can describe the suppression!
Can Pt distribution help us to understand the
production mechanism ?


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            Idea of this work
●J/Ψ is produced via initial gluon fusion,
no coalescence
● J/Ψ transport in QGP and is
anomalously suppressed by gluons
● QGP evolution is controlled by ideal
hydrodynamics
● focus on Pt distribution

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                                                                                  HENP

                   J/Ψ transport equation
          
        p   f  ( x, p, t )  C ( x, p, t ) f  ( x, p, t )
loss term: anomalous suppression
                                  d 3k
         C ( x , p, t )  1              g ( s)4 Fg f g ( x , k , t )
                               (2 ) 2 Ek
                           2        3


                                                                  gluon distribution
                                                        flux factor
                              gluonic dissociation process
Initial condition: normal suppression                   f   nor
                                                                 ( x , p, 0 )
Normal Pt broadening due to Cronin effect
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    Gluonic dissociation process in QGP
                                 g  cc
    standard cross sections: (Bhanot, Peskin,1979)
                    /   1
                                               3/ 2

    g      A               

                      /  
                    0                      5
                                                                : gluon energy
                                                                 : binding energy of J/Ψ


 g     4 A0
                     /        1
                                         1/ 2
                                                9  /    20 / 
                                                                  
                                                                      2
                                                                                      12   
                                                        /  
                                                                      7
                                                                  

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                                                                     HENP

                     Medium evolution
Hydrodynamics:

     T      
                    0, T      
                                     (  p)u u  g          
                                                                     p
                                           
      N  0, N  nu
 EoS: Lattice result
 Initial condition:
             ( 0 ), nb ( 0 ) determined by N p , N c (Kolb, Heinz, Rapp)
 Freeze-out:
                     T f  120 MeV
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           Bjorken space-time evolution
for medium hydrodynamics and J/Ψ transport

                   1 3             t , z, x            1  2  ,x 
     (mt    
               p x ) f  ( x, p, )  C ( x, p, ) f  ( x, p, )
analytic solution
                           
                         0 C ( x v (  '), p , ') / mt d '
f  ( x , p, )  e                                                   f  ( x  v (   0 ), p, 0 )
                                                                        nor


                                                                             Hufner, Zhuang, 2003

   2004-8-16                                 ICHEP04     Beijing                               7
                                           HENP


Suppression and Pt distribution at SPS




             0  0.8 fm,  abs  4.3 mb

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Suppression and Pt distribution at RHIC




                   0  0.6 fm
   J/Ψ formation time > collision time 
                    abs  0
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            Driving force of V2
             y
                                       px  p y
                                        2     2

                     x       v2 
                                       px  p y
                                        2     2


●Primordial production via gluon fusion:
1)leakage effect of anomalous suppression
2)interaction with thermalized partons
However, J/Ψ does not participate in the
collective expansion!
●Statistical production at thermalization:
c quarks participate in the collective expansion!

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                                     HENP


            Elliptic flow at SPS




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                                             HENP


            Elliptic flow at RHIC
                                      Greco, Ko, Rapp




 V2 with primordial production mechanism is
 only 7% of V2 with coalescence mechanism !

2004-8-16         ICHEP04   Beijing            12
                                            HENP

               Conclusions


● J/Ψ transport + medium hydrodynamics
can explain both the suppression and Pt
distribution

● V2 can differentiate initial production
from coalescence at hadronization



  2004-8-16        ICHEP04   Beijing        13

				
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