2004/01/15 by E. L. Bratkovskaya, Elena Bratkovskaya, Bratkovskaya, E. L. +21
Earth and Planetary Sciences · Medicine · Physics and Astronomy · #FOS: Physical sciences #Medical Imaging Techniques and Applications #Nuclear Theory (nucl-th) #Seismic Imaging and Inversion Techniques #nucl-th
paper · pdf · doi:10.48550/arxiv.nucl-th/0401031
17 pages, 7 figures, Invated talk presented by H. Stöcker at the International Conference of the NATO Advanced Study Institute 'Structure and Dynamics of Elementary Matter', Kemer, Turkey, 22 Sep.-20 Okt. 2003 (references corrected in the new version)
openalex publication_date 2004/01/15 · arxiv created 2004/02/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate hadron production and transverse hadron spectra in nucleus-nucleus collisions from 2 A⋅GeV to 21.3 A⋅TeV within two independent transport approaches (UrQMD and HSD) based on quark, diquark, string and hadronic degrees of freedom. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled pp collisions (the 'kink') is described well by both approaches without involving a phase transition. However, the maximum in the K+/π+ ratio at 20 to 30 A⋅GeV (the 'horn') is missed by ∼ 40%. Also, at energies above ∼ 5 A⋅GeV, the measured K± mT-spectra have a larger inverse slope than expected from the models. Thus the pressure generated by hadronic interactions in the transport models at high energies is too low. This finding suggests that the additional pressure - as expected from lattice QCD at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre-hadronic/partonic phase of central heavy-ion collisions. Finally, we discuss the emergence of density perturbations in a first-order phase transition and why they might affect relative hadron multiplicities, collective flow, and hadron mean-free paths at decoupling.