Andrzej Rybicki, Kraków, 6 Feb 2007
Strong and Electromagnetic Interactionsin Heavy-Ion Collisions
Andrzej RybickiDept. of Ultrarelativistic Nuclear Physics
in collaboration with:
Antoni Szczurek, Andrzej GórskiDept. of Strong Interactions and Mechanisms of Nuclear Reactions
H. Niewodniczański Institute of Nuclear Physics of the Polish Academy of Sciences, Kraków
1) Introduction
2) Experimental results
3) Theory
4) Conclusions
Andrzej Rybicki, Kraków, 6 Feb 2007
Introduction: heavy-ion collisions
Proton
● What is the nature
of the strong force?
Nucleus
Andrzej Rybicki, Kraków, 6 Feb 2007
Wounded
Nucleons
● What is the nature
of the strong force?
Nucleus
Spectator system
Produced particles( mesons )
Introduction: heavy-ion collisions
Proton
Andrzej Rybicki, Kraków, 6 Feb 2007
● What is the nature
of the strong force?
Nucleus
Spectator system
+ Pb Pb √s
N+N = 17 GeV
Introduction: heavy-ion collisions
Produced particles( mesons )
Proton
WoundedNucleons
Andrzej Rybicki, Kraków, 6 Feb 2007
NA49 @ CERN SPS (SPS = Super Proton Synchrotron)
The Geneva Lake
LEP/LHC
CERN
Pb beam, 158 GeV/N SPS
Andrzej Rybicki, Kraków, 6 Feb 2007
NA49 @ CERN SPS (SPS = Super Proton Synchrotron)
CERN
The Geneva Lake
LEP/LHC
Pb beam, 158 GeV/N SPS
NA49
Andrzej Rybicki, Kraków, 6 Feb 2007
Experimental Results
Andrzej Rybicki, Kraków, 6 Feb 2007
xF= 0.05
Pb+Pb
xF= 0.10
Pb+Pb
xF= 0.15
Pb+Pb
xF= 0.20
Pb+Pb
xF= 0.25
Pb+Pb
A.Rybicki, to appear in Int. J. Mod. Phys. A, 2007
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
Produced
m/mN = 0.15
MAXL
LF p
p=x
Andrzej Rybicki, Kraków, 6 Feb 2007
A.Rybicki, to appear in Int. J. Mod. Phys. A, 2007
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
Produced
xF= 0.05
Pb+Pb
xF= 0.10
Pb+Pb
xF= 0.15
Pb+Pb
xF= 0.20
Pb+Pb
xF= 0.25
Pb+Pb
m/mN = 0.15
MAXL
LF p
p=x
Andrzej Rybicki, Kraków, 6 Feb 2007
A.Rybicki, to appear in Int. J. Mod. Phys. A, 2007
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
NA49 Preliminary
Produced
Coulomb repulsion ( for ) and attraction ( for )
MAXL
LF p
p=x
m/mN = 0.15
xF= 0.05
Pb+Pb
xF= 0.10
Pb+Pb
xF= 0.15
Pb+Pb
xF= 0.20
Pb+Pb
xF= 0.25
Pb+Pb
Andrzej Rybicki, Kraków, 6 Feb 2007
Theory
Andrzej Rybicki, Kraków, 6 Feb 2007
t = tE
Model of peripheral collision:
● the “spectator systems” are modelled as two spheres;● the pion emission region is reduced to a single point in space;
● the emission time t E is a free parameter.
A.Rybicki, A.Szczurek, nucl-th/0610036, to appear in PRC, 2007
A.Szczurek, A.Rybicki, A.Górski, nucl-th/0701056, to appear in J. Phys. G, 2007
Andrzej Rybicki, Kraków, 6 Feb 2007
x
F
25 MeV/c
75 MeV/c
125 MeV/c
175 MeV/c
325 MeV/c
pT =
t E = 0 fm/c
t E = 1.5 fm/c
t E = 1 fm/c
t E = 0.5 fm/c
t = tE
Strong dependence on initial conditions
Model of peripheral collision:
Andrzej Rybicki, Kraków, 6 Feb 2007
Conclusions
● The interplay between strong and electromagnetic interactions results in visible distortions of the ratios measured in high energy heavy-ion collisions.
● These distortions bring new information on the dynamics of the collision.
Andrzej Rybicki, Kraków, 6 Feb 2007
Acknowledgements
This work was supported by the Polish State Committee for Scientific Research under grant no. 1 P03B 097 29.
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