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A new SPS programme (2006)

Marek Gazdzicki

A new experiemntal program to study hadron production in hadron-nucleus and nucleus-nucleus collisions at the CERN SPS has been recently proposed by the NA49-future collaboration. The physics goals of the program are: (i) search for the critical point of strongly interacting matter and a study of the properties of the onset of deconfinemnt in nucleus-nucleus collisions, (ii) measurements of correlations, fluctuations and hadron spectra at high transverse momentum in proton-nucleus collisions needed as for better understanding of nucleus-nucleus results, (iii) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger Observatory and KASCADE) expriments. The physics of the nucleus-nucleus program is reviewed in this presentation.

Transparency, mixing and reflection of initial flows in relativistic nuclear collisions (2006)

Marek Gazdzicki Mark I. Gorenstein

We propose to use the hadron number fluctuations in the limited momentum regions to study the evolution of initial flows in high energy nuclear collisions. In this method by a proper preparation of a collision sample the projectile and target initial flows are marked in fluctuations in the number of colliding nucleons. We discuss three limiting cases of the evolution of flows, transparency, mixing and reflection, and present for them quantitative predictions obtained within several models. Finally, we apply the method to the NA49 results on fluctuations of the negatively charged hadron multiplicity in Pb+Pb interactions at 158A GeV and conclude that the data favor a hydrodynamical model with a significant degree of mixing of the initial flows at the early stage of collisions.

Energy and system size dependence of chemical freeze-out in relativistic nuclear collisions (2005)

Francesco Becattini Jaakko Manninen Marek Gazdzicki

We present a detailed study of chemical freeze-out in p-p, C-C, Si-Si and Pb-Pb collisions at beam momenta of 158A GeV as well as Pb-Pb collisions at beam momenta of 20A, 30A, 40A and 80A GeV. By analyzing hadronic multiplicities within the statistical hadronization model, we have studied the parameters of the source as a function of the number of the participating nucleons and the beam energy. We observe a nice smooth behaviour of temperature, baryon chemical potential and strangeness under-saturation parameter as a function of energy and nucleus size. Interpolating formulas are provided which allow to predict the chemical freeze-out parameters in central collisions at centre-of-mass energies > 4.5 GeV and for any colliding ions. Specific discrepancies between data and model emerge in particle ratios in Pb-Pb collisions at SPS between 20A and 40A GeV of beam energy which cannot be accounted for in the considered model schemes.

Evidence for an exotic S=-2, Q=-2 baryon resonance in proton-proton collisions at the CERN SPS (2004)

Christopher Alt L. Betev Anja Billmeier Christoph Blume Roland Bramm P. Buncic Peter Dinkelaker Dominik Bernhard Flierl Marek Gazdzicki Stefan Kniege Thorsten Kollegger Christine Meurer Michael Kosta Mitrovski R. Renfordt Reinhard Stock Herbert Ströbele Alexander Albert Wetzler Jacek Zaranek et al. NA49 Collaboration

Results of resonance searches in the Xi - pi -, Xi - pi +, Xi -bar+ pi -, and Xi -bar+ pi + invariant mass spectra in proton-proton collisions at sqrt[s]=17.2 GeV are presented. Evidence is shown for the existence of a narrow Xi - pi - baryon resonance with mass of 1.862±0.002 GeV/c2 and width below the detector resolution of about 0.018 GeV/c2. The significance is estimated to be above 4.2 sigma . This state is a candidate for the hypothetical exotic Xi --3/2 baryon with S=-2, I=3 / 2, and a quark content of (dsdsu-bar). At the same mass, a peak is observed in the Xi - pi + spectrum which is a candidate for the Xi 03/2 member of this isospin quartet with a quark content of (dsusd-bar). The corresponding antibaryon spectra also show enhancements at the same invariant mass.

Analysis of V0-events registered in the streamer spectrometer SKM-200 (2005)

Marek Gazdzicki K. Iovchev E. Okonov T. Tymieniecka

Analysis of Lambda and associative pion production in relativistic nucleus-nucleus collisions (1984)

M. Kh. Anikina Marek Gazdzicki A. Golokhvastov et. al.

Experimental data on pi-mesons produced in inelastic and central nucleus-nucleus interactions at 4.5-Gev/C momentum per nucleon (1984)

M. Kh. Anikina A. Abdurakhimov V. Aksinenko Marek Gazdzicki et. al.

Study of the polarization for Lambda's produced in nucleus-nucleus interactions (1985)

M.Kh. Anikina A. Golokhvastov K. Iovchev S. Khorozov E. Kuznetzova J. Lukstins E. Okonov T. Ostanievich G. Vardenga L. Chkhaidze T. Dzobava Marek Gazdzicki E. Skrzypczak

Peculiarities of Lambda hyperon and Pi meson production in nucleus-nucleus collisions at high energies (1985)

Marek Gazdzicki K. Iovchev E. Kladnitskaya E. Okonov E. Skrzypczak

Charged particle spectra in central S+S collisions at 200 GeV/c per nucleon (1994)

J. Eschke M. Fuchs Marek Gazdzicki W. Heck S. Kabana A. Kühmichel M. Lahanas J. Y. Lee R. Renfordt D. Röhrich G. Roland H. Rothard I. Schneider Reinhard Stock Herbert Ströbele S. Wenig

The transverse momentum and rapidity distributions of negative hadrons and participant protons have been measured for central 32S+ 32S collisions at plab=200 GeV/c per nucleon. The proton mean rapidity shift < Delta y>~1.6 and mean transverse momentum <pT>~0.6 GeV/c are much higher than in pp or peripheral AA collisions and indicate an increase in the nuclear stopping power. All pT spectra exhibit similar source temperatures. Including previous results for K0s Lambda , and Lambda -bar, we account for all important contributions to particle production.

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