Elisabeth Liefmann-Keil: Eine frühe Ordoliberale in dunkler Zeit

Das Jahr 1961 markiert einen Wendepunkt in der deutschsprachigen Sozialpolitiklehre: Das Werk "Ökonomische Theorie der Sozialpolitik", das Elisabeth Liefmann-Keil zu diesem Zeitpunkt veröffentlichte, wurde als Ereignis für die wissenschaftliche Sozialpolitik (Zöllner 1962: 215) und als Anschluß an die internationale Diskussion gefeiert (vgl. Lampert 1992: 120). Zwar war bereits bald nach dem Tod Gustav von Schmollers 1917 im Ausklang der historischen Schule ein heftiger Streit um eine "rationale Sozialpolitik" und deren ökonomisch-theoretische Fundierung entbrannt (vgl. Blümle und Goldschmidt 2003a), doch hatten nicht zuletzt die Wirrungen der nationalsozialistischen, "völkischen" Sozialpolitik, eine frühzeitige Rezeption angelsächsischer, neoklassischer Literatur auch für dieses Feld der Wirtschaftswissenschaften in der Nachkriegszeit erschwert

Nonlinear looped band structure of Bose-Einstein condensates in an optical lattice

We study experimentally the stability of excited, interacting states of bosons in a double-well optical lattice in regimes where the nonlinear interactions are expected to induce "swallowtail" looped band structure. By carefully preparing different initial coherent states and observing their subsequent decay, we observe distinct decay rates that provide direct evidence for multivalued, looped band structure. The double well lattice both stabilizes the looped band structure and allows for dynamic preparation of different initial states, including states within the loop structure. We confirm our state preparation procedure with dynamic Gross-Pitaevskii calculations. The excited loop states are found to be more stable than dynamically unstable ground states, but decay faster than expected based on a mean-field stability calculation, indicating the importance of correlations beyond a mean field description.Comment: 6 pages, 6 figure

Critical Behavior of Disordered Systems with a Free Surface

The behavior of homogeneous and disordered systems with a free boundary is described on the basis of group theory in the two-loop approximation directly in three-dimensional space. The effect of the free boundary on the regime of the bulk critical behavior is revealed. It is shown that the boundedness of the system slightly affects the regime of the bulk critical behavior in the case of the ordinary transition, whereas this effect is more noticeable in the case of the special transition. Surface critical phenomena are described for homogeneous and disordered systems, and the critical exponents are calculated in the two-loop approximation. It is shown that the effect of impurities is insignificant in the special phase transition, whereas it is more noticeable in the ordinary phase transition. The derived critical exponents are compared with the computer-simulation results.Comment: 19 pages, 2 figure

Three-Dimensional Integrable Models and Associated Tangle Invariants

In this paper we show that the Boltzmann weights of the three-dimensional Baxter-Bazhanov model give representations of the braid group, if some suitable spectral limits are taken. In the trigonometric case we classify all possible spectral limits which produce braid group representations. Furthermore we prove that for some of them we get cyclotomic invariants of links and for others we obtain tangle invariants generalizing the cyclotomic ones.Comment: Number of pages: 21, Latex fil

Elisabeth Liefmann-Keil: Eine frühe Ordoliberale in dunkler Zeit

Das Jahr 1961 markiert einen Wendepunkt in der deutschsprachigen Sozialpolitiklehre: Das Werk "Ökonomische Theorie der Sozialpolitik", das Elisabeth Liefmann-Keil zu diesem Zeitpunkt veröffentlichte, wurde als ?Ereignis für die wissenschaftliche Sozialpolitik? (Zöllner 1962: 215) und als ?Anschluß an die internationale Diskussion? gefeiert (vgl. Lampert 1992: 120). Zwar war bereits bald nach dem Tod Gustav von Schmollers 1917 im Ausklang der historischen Schule ein heftiger Streit um eine "rationale Sozialpolitik" und deren ökonomisch-theoretische Fundierung entbrannt (vgl. Blümle und Goldschmidt 2003a), doch hatten nicht zuletzt die Wirrungen der nationalsozialistischen, "völkischen" Sozialpolitik, eine frühzeitige Rezeption angelsächsischer, neoklassischer Literatur auch für dieses Feld der Wirtschaftswissenschaften in der Nachkriegszeit erschwert. --

Particle production and equilibrium properties within a new hadron transport approach for heavy-ion collisions

The microscopic description of heavy-ion reactions at low beam energies is achieved within hadronic transport approaches. In this article a new approach SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) is introduced and applied to study the production of non-strange particles in heavy-ion reactions at $E_{\rm kin}=0.4-2A$ GeV. First, the model is described including details about the collision criterion, the initial conditions and the resonance formation and decays. To validate the approach, equilibrium properties such as detailed balance are presented and the results are compared to experimental data for elementary cross sections. Finally results for pion and proton production in C+C and Au+Au collisions is confronted with HADES and FOPI data. Predictions for particle production in $\pi+A$ collisions are made.Comment: 30 pages, 30 figures, replaced with published version; only minor change

Sigma models as perturbed conformal field theories

We show that two-dimensional sigma models are equivalent to certain perturbed conformal field theories. When the fields in the sigma model take values in a space G/H for a group G and a maximal subgroup H, the corresponding conformal field theory is the $k\to\infty$ limit of the coset model $(G/H)_k$, and the perturbation is related to the current of G. This correspondence allows us for example to find the free energy for the "O(n)" (=O(n)/O(n-1)) sigma model at non-zero temperature. It also results in a new approach to the CP^{n} model.Comment: 4 pages. v2: corrects typos (including several in the published version