TY  - JOUR
A1  - Bratkovskaya, Elena L.
A1  - Soff, Sven
A1  - Stöcker, Horst
A1  - Leeuwen, Marco van
A1  - Cassing, Wolfgang
T1  - Evidence for nonhadronic degrees of freedom in the transverse mass spectra of kaons from relativistic nucleus-nucleus collisions?
T2  - Physical review letters
N2  - We investigate transverse hadron spectra from relativistic nucleus-nucleus collisions which reflect important aspects of the dynamics - such as the generation of pressure - in the hot and dense zone formed in the early phase of the reaction. Our analysis is performed within two independent transport approaches (HSD and UrQMD) that are based on quark, diquark, string and hadronic degrees of freedom. Both transport models show their reliability for elementary pp as well as light-ion (C+C, Si+Si) reactions. However, for central Au+Au (Pb+Pb) collisions at bombarding energies above ~ 5 A.GeV the measured K+- transverse mass spectra have a larger inverse slope parameter than expected from the calculation. Thus the pressure generated by hadronic interactions in the transport models above ~ 5 A.GeV is lower than observed in the experimental data. This finding shows that the additional pressure - as expected from lattice QCD calculations at finite quark chemical potential and temperature - is generated by strong partonic interactions in the early phase of central Au+Au (Pb+Pb) collisions.
Y1  - 2005
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/4818
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30-6837
SN  - 1079-7114
SN  - 0031-9007
N1  - ©2004 American Physical Society
VL  - 92
IS  - 3, Art. 032302
SP  - 1
EP  - 4
PB  - American Physical Society
CY  - College Park, Md.
ER  -