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.