Dynamics of K+K^+ Production in Heavy Ion Collisions close to Threshold

In this article the production of $K^+$ at energies close to the threshold is studied in detail. The production mechanisms, the influence of in-medium effects, cross sections, the nuclear equation of state and the dynamics of the nucleons on the kaon dynamics are discussed. A special regard will be taken on the collision of Au+Au at 1.5 GeV, a reaction that has recently been analyzed in detail by experiments performed by the KaoS and FOPI collaborations at the SIS accelerator at GSI.Comment: extract from habilitation at Nantes university (France), 76 pages, 76 figures, ps-file about 6M

Spectral ratio: an observable to determine K+K^{+} nucleus potential and K+K^{+} N scattering cross section

Here we aim to show that the ratio of the momentum spectra of $K^{+}$ at small transverse momentum measured for symmetric systems of different sizes can be such an observable.Comment: 3 pages, 2 figs, DAE BRNS Symposium on Nuclear Physics Dec 26-30, (2011), Visakhapatnam A.P. INDI

Felt-bodily didactics. Educational processes from a subjective-bodily phenomenological perspective

Der Beitrag geht davon aus, dass Bildungsprozesse als Auseinandersetzung des Subjektes mit sich selbst und der Welt stets leiblich vermittelte Prozesse sind. Für die Didaktik bedeutet dies, dass Lehrmethoden und Lerninhalte stets in Kontexte eingebunden werden müssen, welche die Schülerinnen und Schüler leiblich-affektiv ergreifen. Aufbauend auf den leibphänomenologischen Überlegungen von Hermann Schmitz (2008), wird das leibliche Lernen in personaler Regression und Emanzipation betrachtet und es werden Überlegungen zur Haltung der Lehrkraft angestellt, welche die Schülerinnen und Schüler begleiten und Lerninhalte wie Räume atmosphärisch einbetten sollte. Schließlich werden einige gängige Praxisbeispiele gegeben, welche die Ideen einer leiblichen Didaktik´ für den Schulalltag verdeutlichen sollen. (DIPF/Orig.)The article assumes that educational processes – as an examination between the subject, itself, and the world – always are subjective-bodily mediated processes. Regarding didactics, this means that teaching methods and learning contents always need to be integrated into contexts which the students take subjective-bodily affectively. Based on Hermann Schmitz\u27s subjective-bodily phenomenological reflections (2008), physical learning is considered in personal regression and emancipation, and considerations are being made on the attitude of the teacher which should accompany the students and embed learning contents and spaces atmospherically. In the end, some common practice examples are given to illustrate the ideas of subjective-bodily didactics for the everyday school life. (Author

Analysis of Dilepton Invariant Mass Spectrum in C+C at 2 and 1 AGeV

Recently the HADES collaboration has published the invariant mass spectrum of $e^+e^-$ pairs, dN/dM$_{e^+e^-}$, produced in C+C collisions at 2 AGeV. Using electromagnetic probes, one hopes to get in this experiment information on hadron properties at high density and temperature. Simulations show that firm conclusions on possible in-medium modifications of meson properties will only be possible when the elementary meson production cross sections, especially in the pn channel, as well as production cross sections of baryonic resonances are better known. Presently one can conclude that a) simulations overpredict by far the cross section at $M_{e^+e^-} \approx M_{\omega}{^0}$ if free production cross sections are used and that b) the upper limit of the $\eta$ decay into $e^+e^-$ is smaller than the present upper limit of the Particle Data Group. This is the result of simulations using the Isospin Quantum Molecular Dynamics (IQMD) approach.Comment: 28 pages, 15 figures, 3 tables, ps file recommende

Azimuthal correlations of pions in relativistic heavy ion collisions at 1 GeV/nucl.

Triple differential cross sections of pions in heavy ion collisions at 1 GeV/nucl. are studied with the IQMD model. After discussing general properties of resonance and pion production we focus on azimuthal correlations: At projectile- and target-rapidities we observe an anticorrelation in the in-plane transverse momentum between pions and protons. At c.m.-rapidity, however, we find that high pt pions are being preferentially emitted perpendicular to the event-plane. We investigate the causes of those correlations and their sensitivity on the density and momentum dependence of the real and imaginary part of the nucleon and pion optical potential

Out-of-plane pion emission in relativistic heavy ion collisions: Spectroscopy of Delta resonance matter

Azimuthal correlations of pions are studied with the quantum molecular dynamics model. Pions are preferentially emitted perpendicular to the reaction plane. Our analysis shows that this anisotropy is dominated by pion absorption on the spectator matter in the reaction plane. Pions emitted perpendicular to the reaction plane undergo less rescattering than those emitted in the reaction plane and might therefore be more sensitive to the early hot and dense reaction phase

Landau-Vlasov model versus Vlasov-Uehling-Uhlenbeck-approach : different flow effects from the same theory?

Differences between the Nantes-Ganil-Grenoble (NGG) LV-model and the original VUU approach are analysed. It is found that the LV code tends to simulate - for small timesteps - a non-viscous testparticle fluid

The multifragmentation of spectator matter

We present the first microscopic calculation of the spectator fragmentation observed in heavy ion reactions at relativistic energies which reproduces the slope of the kinetic energy spectra of the fragments as well as their multiplicity, both measured by the ALADIN collaboration. In the past both have been explained in thermal models, however with vastly different assumptions about the excitation energy and the density of the system. We show that both observables are dominated by dynamical processes and that the system does not pass a state of thermal equilibrium. These findings question the recent conjecture that in these collisions a phase transition of first order, similar to that between water and vapor, can be observed.Comment: 7 page

Kaon production at subthreshold and threshold energies

We summarize what we have learnt about the kaon production in nucleus-nucleus collisions in the last decade. We will address three questions: a) Is the $K^+$ production sensitive to the nuclear equation of state? b) How can it happen that at the same excess energy the same number of $K^+$ and $K^-$ are produced in heavy ion collisions although the elementary cross section in pp collisions differs by orders of magnitudes? and c) Why kaons don't flow?Comment: 5 pages, 4 figures, contribution to Strange Quark Matter 200

On the flow of kaons produced in relativistic heavy ion collisions

We investigate the different contributions to the in-plane flow of K+ mesons observed recently by the FOPI collaboration in the reaction Ni(1.93 AGeV)+Ni. Due to the kinematics of the three body phase space decay the flow of kaons produced in baryon-baryon interactions is smaller than that of the baryons in the entrance channel. On the contrary, in pi N interactions the flow of the sources and of the kaons are identical. Therefore the total kaon flow depends on the relative number of Delta N -> K+ and pi N -> K+ reactions and hence on the lifetime of the Delta, in addition to the already known dependence on the potential interaction interaction of the kaons with the nuclear environment.Comment: 11 pages, 10 figures, submitted to NP