TY - JOUR A1 - Gaździcki, Marek T1 - Strangeness and pion production as signals of QCD phase transition T2 - Talk given at International Symposium on Strangeness in Quark Matter 1997, Thera (Santorini), Greece, April 14~V18, 1997 N2 - A systematic analysis of data on strangeness and pion production in nucleon–nucleon and central nucleus–nucleus collisions is presented. It is shown that at all collision energies the pion/baryon and strangeness/pion ratios indicate saturation with the size of the colliding nuclei. The energy dependence of the saturation level suggests that the transition to the Quark Gluon Plasma occurs between 15 A·GeV/c (BNL AGS) and 160 A·GeV/c (CERN SPS) collision energies. The experimental results interpreted in the framework of a statistical approach show that the effective number of degrees of freedom increases in the course of the phase transition and that the plasma created at CERN SPS energies may have a temperature of about 280 MeV (energy density ~ 10 GeV/fm exp-3). The presence of the phase transition can lead to the non–monotonic collision energy dependence of the strangeness/pion ratio. After an initial increase the ratio should drop to the characteristic value for the QGP. Above the transition region the ratio is expected to be collision energy independent. Experimental studies of central Pb+Pb collisions in the energy range 20–160 A·GeV/c are urgently needed in order to localize the threshold energy, and study the properties of the QCD phase transition. Y1 - 2005 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/4058 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30-14368 UR - http://arxiv.org/PS_cache/nuclth/pdf/9706/9706036.pdf ER -