Darmstadt 2008 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Physik mit schweren Ionen
HK 13.7: Talk
Monday, March 10, 2008, 18:15–18:30, 2E
Two- and three particle correlations of high-pt charged particles in heavy ion collisions at CERN SPS energy* — Stefan Kniege, •Dariusz Antonczyk, Harald Appelshäuser, and Simone Schuchmann for the CERES collaboration — Institut für Kernphysik Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt a.M.
The analysis of azimuthal correlations of hadrons with high transverse
momenta provide a unique tool to study the interactions of partons
with the medium in an early stage of heavy ion collisions.
A detailed analysis of two particle correlations in Pb-Au collisions
from the CERES experiment at top SPS energy will be presented.
The key observation is a non-Gaussian shape on the
"away-side" of the two particle correlation function in central collisions
indicating significant interactions of partons traversing the medium
even at SPS energy.
A study of the correlations for different charge combinations
of trigger and associate particles reveals charge ordering
in the fragmentation process and sensitivity to the charges of the
interacting partons. Hence the analysis may reveal properties of the
initial as well as the final state of the collision.
To further investigate the pattern of the two particle correlation
function an analysis based on three particle correlations is presented.
Different scenarios like elastic scattering of the initial partons
or the evolution of a mach cone can lead to the same observable
shape of the two particle correlation function.
The three particle
analysis presented gives strong indications for a cone like emission of hadrons
emerging from hard parton-parton interactions in the collisions.
This work was supported by BMBF, GSI and H-QM.