Year of publication
- On transverse momentum event–by–event fluctuations in string hadronic models (1998)
- Transverse momentum event-by-event fluctuations are studied within the string-hadronic model of high energy nuclear collisions, LUCIAE. Data on non-statistical pT fluctuations in p+p interactions are reproduced. Fluctuations of similar magnitude are predicted for nucleus-nucleus collisions, in contradiction to the preliminary NA49 results. The introduction of a string clustering mechanism (Firecracker Model) leads to a further, significant increase of pT fluctuations for nucleus-nucleus collisions. Secondary hadronic interactions, as implemented in LUCIAE, cause only a small reduction of pT fluctuations.
- On the measurement of D-meson yield in nucleus-nucleus collisions at the CERN SPS (1999)
- We argue that the measurement of open charm gives a unique opportunity to test the validity of pQCD-based and statistical models of nucleus-nucleus collisions at high energies. We show that various approaches used to estimate D-meson multiplicity in central Pb+Pb collisions at 158 A GeV give predictions which differ by more than a factor of 100. Finally we demonstrate that decisive experimental results concerning the open charm yield in A+A collisions can be obtained using data of the NA49 experiment at the CERN SPS.
- Strangeness and pion production as signals of QCD phase transition (1997)
- 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.
- Fluctuations and NA49 (2005)
- A brief history of the study of fluctuations in high energy nuclear collisions at the CERN SPS performed by NA49 is presented. The ideas and the corresponding experimental data on fluctuations are discussed from the point of view of their sensitivity to the onset of deconfinement.
- Study on chemical equilibrium in nucleus-nucleus collisions at relativistic energies (2004)
- We present a detailed study of chemical freeze-out in nucleus-nucleus collisions at beam energies of 11.6, 30, 40, 80 and 158A GeV. By analyzing hadronic multiplicities within the statistical hadronization approach, we have studied the chemical equilibration of the system as a function of center of mass energy and of the parameters of the source. Additionally, we have tested and compared different versions of the statistical model, with special emphasis on possible explanations of the observed strangeness hadronic phase space under-saturation.