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The data on mT spectra of K0S K+ and K- mesons produced in all inelastic p + p and p + pbar interactions in the energy range sqrt(s)NN=4.7-1800GeV are compiled and analyzed. The spectra are parameterized by a single exponential function, dN/(m_T*dm_T)=C exp(-m_T/T), and the inverse slope parameter T is the main object of study. The T parameter is found to be similar for K0S, K+ and K- mesons. It increases monotonically with collision energy from T~30MeV at sqrt(s)NN=4.7GeV to T~220MeV at sqrt(s)NN=1800GeV. The T parameter measured in p+p and p+pbar interactions is significantly lower than the corresponding parameter obtained for central Pb+Pb collisions at all studied energies. Also the shape of the energy dependence of T is different for central Pb+Pb collisions and p+p(pbar) interactions.
We propose a method to experimentally study the equation of state of strongly interacting matter created at the early stage of nucleus--nucleus collisions. The method exploits the relation between relative entropy and energy fluctuations and equation of state. As a measurable quantity, the ratio of properly filtered multiplicity to energy fluctuations is proposed. Within a statistical approach to the early stage of nucleus-nucleus collisions, the fluctuation ratio manifests a non--monotonic collision energy dependence with a maximum in the domain where the onset of deconfinement occurs.
Production of Lambda and Antilambda hyperons was measured in central Pb-Pb collisions at 40, 80, and 158 A GeV beam energy on a fixed target. Transverse mass spectra and rapidity distributions are given for all three energies. The Lambda/pi ratio at mid-rapidity and in full phase space shows a pronounced maximum between the highest AGS and 40 A GeV SPS energies, whereas the anti-Lambda}/pi ratio exhibits a monotonic increase. PACS numbers: 25.75.-q
Fluctuations of charged particle number are studied in the canonical ensemble. In the infinite volume limit the fluctuations in the canonical ensemble are different from the fluctuations in the grand canonical one. Thus, the well-known equivalence of both ensembles for the average quantities does not extend for the fluctuations. In view of a possible relevance of the results for the analysis of fluctuations in nuclear collisions at high energies, a role of the limited kinematical acceptance is studied.
Report from NA49
(2004)
The most recent data of NA49 on hadron production in nuclear collisions at CERN SPS energies are presented. Anomalies in the energy dependence of pion and kaon production in central Pb+Pb collisions are observed. They suggest that the onset of deconfinement is located at about 30 AGeV. Large multiplicity and transverse momentum fluctuations are measured for collisions of intermediate mass systems at 158 AGeV. The need for a new experimental programme at the CERN SPS is underlined.
The transverse mass mt distributions for deuterons and protons are measured in Pb+Pb reactions near midrapidity and in the range 0<mt–m<1.0 (1.5) GeV/c2 for minimum bias collisions at 158A GeV and for central collisions at 40 and 80 A GeV beam energies. The rapidity density dn/dy, inverse slope parameter T and mean transverse mass <mt> derived from mt distributions as well as the coalescence parameter B2 are studied as a function of the incident energy and the collision centrality. The deuteron mt spectra are significantly harder than those of protons, especially in central collisions. The coalescence factor B2 shows three systematic trends. First, it decreases strongly with increasing centrality reflecting an enlargement of the deuteron coalescence volume in central Pb+Pb collisions. Second, it increases with mt. Finally, B2 shows an increase with decreasing incident beam energy even within the SPS energy range. The results are discussed and compared to the predictions of models that include the collective expansion of the source created in Pb+Pb collisions.
Preliminary results on pion-pion Bose-Einstein correlations in central Pb+Pb collisions measured by the NA49 experiment are presented. Rapidity as well as transverse momentum dependence of the HBT-radii are shown for collisions at 20, 30, 40, 80, and 158 AGeV beam energy. Including results from AGS and RHIC experiments only a weak energy dependence of the radii is observed. Based on hydrodynamical models parameters like lifetime and geometrical radius of the source are derived from the dependence of the radii on transverse momentum.
Event-by-event fluctuations of particle ratios in central Pb + Pb collisions at 20 to 158 AGeV
(2004)
In the vicinity of the QCD phase transition, critical fluctuations have been predicted to lead to non-statistical fluctuations of particle ratios, depending on the nature of the phase transition. Recent results of the NA49 energy scan program show a sharp maximum of the ratio of K+ to Pi+ yields in central Pb+Pb collisions at beam energies of 20-30 AGeV. This observation has been interpreted as an indication of a phase transition at low SPS energies. We present first results on event-by-event fluctuations of the kaon to pion and proton to pion ratios at beam energies close to this maximum.
Results are presented on event-by-event electric charge fluctuations in central Pb+Pb collisions at 20, 30, 40, 80 and 158 AGeV. The observed fluctuations are close to those expected for a gas of pions correlated by global charge conservation only. These fluctuations are considerably larger than those calculated for an ideal gas of deconfined quarks and gluons. The present measurements do not necessarily exclude reduced fluctuations from a quark-gluon plasma because these might be masked by contributions from resonance decays.
System size and centrality dependence of the balance function in A + A collisions at √sNN = 17.2 GeV
(2004)
Electric charge correlations were studied for p+p, C+C, Si+Si and centrality selected Pb+Pb collisions at sqrt s_NN = 17.2$ GeV with the NA49 large acceptance detector at the CERN-SPS. In particular, long range pseudo-rapidity correlations of oppositely charged particles were measured using the Balance Function method. The width of the Balance Function decreases with increasing system size and centrality of the reactions. This decrease could be related to an increasing delay of hadronization in central Pb+Pb collisions.
The hadronic final state of central Pb+Pb collisions at 20, 30, 40, 80, and 158 AGeV has been measured by the CERN NA49 collaboration. The mean transverse mass of pions and kaons at midrapidity stays nearly constant in this energy range, whereas at lower energies, at the AGS, a steep increase with beam energy was measured. Compared to p+p collisions as well as to model calculations, anomalies in the energy dependence of pion and kaon production at lower SPS energies are observed. These findings can be explained, assuming that the energy density reached in central A+A collisions at lower SPS energies is sufficient to force the hot and dense nuclear matter into a deconfined phase.
System size dependence of multiplicity fluctuations of charged particles produced in nuclear collisions at 158 A GeV was studied in the NA49 CERN experiment. Results indicate a non-monotonic dependence of the scaled variance of the multiplicity distribution with a maximum for semi-peripheral Pb+Pb interactions with number of projectile participants of about 35. This effect is not observed in a string-hadronic model of nuclear collision HIJING.
The hadronic final state of central Pb+Pb collisions at 20, 30, 40, 80, and 158 AGeV has been measured by the CERN NA49 collaboration. The mean transverse mass of pions and kaons at midrapidity stays nearly constant in this energy range, whereas at lower energies, at the AGS, a steep increase with beam energy was measured. Compared to p+p collisions as well as to model calculations, anomalies in the energy dependence of pion and kaon production at lower SPS energies are observed. These findings can be explained, assuming that the energy density reached in central A+A collisions at lower SPS energies is sufficient to transform the hot and dense nuclear matter into a deconfined phase.
In the early Nineties the Hague Conference on International Private Law on initiative of the United States started negotiations on a Convention on the Recognition and Enforcement of Foreign Judgments in Civil and Commercial Matters (the "Hague Convention"). In October 1999 the Special Commission on duty presented a preliminary text, which was drafted quite closely to the European Convention on Jurisdiction and Enforcement of Judgments in Civil and Commercial Matters (the "Brussels Convention"). The latter was concluded between the then 6 Member States of the EEC in Brussels in 1968 and amended several times on occasion of the entry of new Member States. In 2000, after the Treaty of Amsterdam altered the legal basis for judicial co-operation in civil matters in Europe, it was transformed into an EC Regulation (the "Brussels I Regulation"). The 1999 draft of the Hague Convention was heavily criticized by the USA and other states for its European approach of a double convention, regulating not only the recognition and enforcement of judgments, but at the same time the extent of and the limits to jurisdiction to adjudicate in international cases. During a diplomatic conference in June 2001 a second draft was presented which contained alternative versions of several articles and thus resembled more the existing dissent than a draft convention would. Difficulties to reach a consensus remained, especially with regard to activity based jurisdiction, intellectual property, consumer rights and employee rights. In addition, the appropriateness of the whole draft was questioned in light of the problems posed by the de-territorialization of relevant conduct through the advent of the Internet. In April 2002 it was decided to continue negotiations on an informal level on the basis of a nucleus approach. The core consensus as identified by a working group, however, was not very broad. The experts involved came to the conclusion that the project should be limited to choice of court agreements. In March 2004 a draft was presented which sets out its aims as follows: "The objective of the Convention is to make exclusive choice of court agreements as effective as possible in the context of international business. The hope is that the Convention will do for choice of court agreements what the New York Convention of 1958 has done for arbitration agreements." In April 2004 the Special Commission of the Hague Conference adopted a Draft "Convention on Exclusive Choice of Court Agreements", which according to its Art. 2 No. 1 a) is not applicable to choice of court agreements, to which a natural person acting primarily for personal, family or household purposes (a consumer) is a party". The broader project of a global judgments convention thus seems to be abandoned, or at least to be postponed for an unlimited time period. There are - of course - several reasons why the Hague Judgments project failed. Samuel Baumgartner has described an important one as the "Justizkonflikt" between the United States and Europe or, more specifically Germany. Within the context of the general topic of this conference, that is (international) jurisdiction for human rights, in the remainder of this presentation I shall elaborate on the socio-cultural aspects of the impartiality of judgments and their enforcement on a global scale.
In April 2003 I commented on the European Commission’s Action Plan on a More Coherent European Contract Law [COM(2003) 68 final] and the Green Paper on the Modernisation of the 1980 Rome Convention [COM(2002) 654 final].1 While the main argument of that paper, i.e. the common neglect of the inherent interrelation between both the further harmonisation of substantive contract law by directives or through an optional European Civil Code on the one hand and the modernisation of conflict rules for consumer contracts in Art. 5 Rome Convention on the other hand, remain pressing issues, and as the German Law Journal continues its efforts in offering timely and critical analysis on consumer law issues,2 there is a variety of recent developments worth noting.
We present simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the Arctic winter 2002/2003. We integrated a Lagrangian denitrification scheme into the three-dimensional version of CLaMS that calculates the growth and sedimentation of nitric acid trihydrate (NAT) particles along individual particle trajectories. From those, we derive the HNO3 downward flux resulting from different particle nucleation assumptions. The simulation results show a clear vertical redistribution of total inorganic nitrogen (NOy), with a maximum vortex average permanent NOy removal of over 5 ppb in late December between 500 and 550 K and a corresponding increase of NOy of over 2 ppb below about 450 K. The simulated vertical redistribution of NOy is compared with balloon observations by MkIV and in-situ observations from the high altitude aircraft Geophysica. Assuming a globally uniform NAT particle nucleation rate of 3.4·10−6 cm−3 h−1 in the model, the observed denitrification is well reproduced. In the investigated winter 2002/2003, the denitrification has only moderate impact (<=10%) on the simulated vortex average ozone loss of about 1.1 ppm near the 460 K level. At higher altitudes, above 600 K potential temperature, the simulations show significant ozone depletion through NOx-catalytic cycles due to the unusual early exposure of vortex air to sunlight.
Configuration, simulation and visualization of simple biochemical reaction-diffusion systems in 3D
(2004)
Background In biological systems, molecules of different species diffuse within the reaction compartments and interact with each other, ultimately giving rise to such complex structures like living cells. In order to investigate the formation of subcellular structures and patterns (e.g. signal transduction) or spatial effects in metabolic processes, it would be helpful to use simulations of such reaction-diffusion systems. Pattern formation has been extensively studied in two dimensions. However, the extension to three-dimensional reaction-diffusion systems poses some challenges to the visualization of the processes being simulated. Scope of the Thesis The aim of this thesis is the specification and development of algorithms and methods for the three-dimensional configuration, simulation and visualization of biochemical reaction-diffusion systems consisting of a small number of molecules and reactions. After an initial review of existing literature about 2D/3D reaction-diffusion systems, a 3D simulation algorithm (PDE solver), based on an existing 2D-simulation algorithm for reaction-diffusion systems written by Prof. Herbert Sauro, has to be developed. In a succeeding step, this algorithm has to be optimized for high performance. A prototypic 3D configuration tool for the initial state of the system has to be developed. This basic tool should enable the user to define and store the location of molecules, membranes and channels within the reaction space of user-defined size. A suitable data structure has to be defined for the representation of the reaction space. The main focus of this thesis is the specification and prototypic implementation of a suitable reaction space visualization component for the display of the simulation results. In particular, the possibility of 3D visualization during course of the simulation has to be investigated. During the development phase, the quality and usability of the visualizations has to be evaluated in user tests. The simulation, configuration and visualization prototypes should be compliant with the Systems Biology Workbench to ensure compatibility with software from other authors. The thesis is carried out in close cooperation with Prof. Herbert Sauro at the Keck Graduate Institute, Claremont, CA, USA. Due to this international cooperation the thesis will be written in English.
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.
New results on the production of Xi and Omega hyperons in Pb+Pb interactions at 40 A GeV and Lambda at 30 A GeV are presented. Transverse mass spectra as well as rapidity spectra of these hyperons are shown and compared to previously measured data at different beam energies. The energy dependence of hyperon production (4Pi yields) is discussed. Additionally, the centrality dependence of Xi- production at 40 A GeV is presented.