Fission barriers and asymmetric ground states in the relativistic mean field theory

The symmetric and asymmetric fission path for 240Pu, 232Th, and 226Ra is investigated within the relativistic mean field model. Standard parametrizations which are well fitted to nuclear ground state properties are found to deliver reasonable qualitative and quantitative features of fission, comparable to similar nonrelativstic calculations. Furthermore, stable octupole deformations in the ground states of Radium isotopes are investigated. They are found in a series of isotopes, qualitatively in agreement with nonrelativistic models. But the quantitative details differ amongst the models and between the various relativsitic parametrizations.Comment: 30 pages RevTeX, 7 tables, 12 low resolution Gif figures (high resolution PostScript versions are available at http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html or at ftp://th.physik.uni-frankfurt.de/pub/bender

Brauchen wir eine "neue Soziale Marktwirtschaft"?

The "German economic miracle” after the second world war is connected with the design of an economic policy labeled "Social Market Economy" which forms a third path between capitalism (pure or free market economy) and socialism (centrally planned economy). This notion is relevant for New Labor in Britain as well as for the Social Democrats in Germany. Social Market Economy is usually perceived as an idea aimed at reaching social justice and national peace and thus avoiding the traditional class struggle between capital and labor. However, this idea also requires a change in the paradigm of economic thinking from traditional self-organization by markets to a mixture of social control of both government and markets. Until now, however, economic theory has refused to follow this new paradigm, thus resulting in a deficiency of theory in the field of Social Market Economy. Microeconomic theory is dominating the current economic thinking. The realization of a "socially responsible market economy” should be done pragmatically by political recognition of changing challenges and situations, thus establishing the welfare state in democratic decisions. History has shown that governments have often alternated between the right wing and the left wing. During the sixties, the Social Democrats retained the well established concepts of a Social Market Economy, but attempted to design a "left wing” version thereof, aimed at more political control. In Germany, suffering from the first great crisis in the Federal Republic, this was done in order to reach a higher degree of economic stability. The ensuing governments, led by the Christian Democrats in Germany, attempted to reduce the welfare state using the slogan "more market, less state”. Not even the great challenge of transforming the former socialist parts of Germany into a market economy gave rise to the idea of a "new Social Market Economy”. Similarly, it is argued in this paper that there is no need for a "new Social Market Economy”: The old one is open for reforms from the left as well as from the right wing as experience over more than 50 years has demonstrated. The original Social Market Economy is worth being defended even in view of globalization and is recommended for many economies all over the world in order to avoid globalization of the traditional "class struggle” between capital and labor. A necessary condition for any "socially controlled market economy” are properly working political institutions and governments. Therefore, in order to ensure the necessary public interventions, national states must not vanish, as prophets of globalization often maintain. On the contrary, a political countervailing power is necessary to discipline the "global economic players” as well as to avoid political hegemony of one or more national states. In a global world, only the national states can guarantee decisions along the so called "subsidiary principle” of Social Market Economy.reine Marktwirtschaft , Soziale Marktwirtschaft, Paradigmenwechsel, dritter Weg, dialektischer Prozess, Wohlfahrtsstaat, Subsidiaritaetsprinzip

Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge

Solutions for the three-gluon and quark-gluon vertices from Dyson-Schwinger equations and the three-particle irreducible formalism are discussed. Dynamical quarks (``unquenching'') change the three-gluon vertex via the quark-triangle diagrams which themselves include fully dressed quark-gluon vertex functions. On the other hand, the quark-swordfish diagram is, at least with the model used for the two-quark-two-gluon vertex employed here, of minor importance. For the leading tensor structure of the three-gluon vertex the "unquenching" effect can be summarized for the nonperturbative part as a shift of the related dressing function towards the infrared.Comment: Talk given by Adrian L. Blum at XIIth Quark Confinement and the Hadron Spectrum, August 28 - September 04, 2016, Thessaloniki, Greec

Nuclear Giant Resonances and Linear Response

We search for nonlinear effects in nuclear giant resonances (GRs), in particular the isovector dipole and the isoscalar quadrupole modes. To that end, we employ a spectral analysis of time-dependent Hartree-Fock (TDHF) dynamics using Skyrme forces. Based on TDHF calculations over a wide range of excitation amplitudes, we explore the collectivity and degree of harmonic motion in these modes. Both GR modes turn out to be highly harmonic in heavy nuclei from A=100 on. There is no trace of a transition to irregular motion and multiple resonances are predicted. Slight anharmonicities are seen for light nuclei, particularly for $^{16}$O. These are mainly caused by the spin-orbit splitting.Comment: 5 page

The two-proton shell gap in Sn isotopes

We present an analysis of two-proton shell gaps in Sn isotopes. As the theoretical tool we use self-consistent mean-field models, namely the relativistic mean-field model and the Skyrme-Hartree-Fock approach, both with two different pairing forces, a delta interaction (DI) model and a density-dependent delta interaction (DDDI). We investigate the influence of nuclear deformation as well as collective correlations and find that both effects contribute significantly. Moreover, we find a further significant dependence on the pairing force used. The inclusion of deformation plus correlation effects and the use of DDDI pairing provides agreement with the data.Comment: gzipped tar archiv containing LaTeX source, bibliography file (*.bbl), all figures as *.eps, and the style file

An HFB scheme in natural orbitals

We present a formulation of the Hartree-Fock-Bogoliubov (HFB) equations which solves the problem directly in the basis of natural orbitals. This provides a very efficient scheme which is particularly suited for large scale calculations on coordinate-space grids.Comment: 5 pages RevTeX, (Postscript-file also available at http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html or at ftp://th.physik.uni-frankfurt.de/pub/bender ), accepted for publication in Z. Phys.

Potential energy surfaces of superheavy nuclei

We investigate the structure of the potential energy surfaces of the superheavy nuclei 258Fm, 264Hs, (Z=112,N=166), (Z=114,N=184), and (Z=120,N=172) within the framework of self-consistent nuclear models, i.e. the Skyrme-Hartree-Fock approach and the relativistic mean-field model. We compare results obtained with one representative parametrisation of each model which is successful in describing superheavy nuclei. We find systematic changes as compared to the potential energy surfaces of heavy nuclei in the uranium region: there is no sufficiently stable fission isomer any more, the importance of triaxial configurations to lower the first barrier fades away, and asymmetric fission paths compete down to rather small deformation. Comparing the two models, it turns out that the relativistic mean-field model gives generally smaller fission barriers.Comment: 8 pages RevTeX, 6 figure

Superheavy nuclei in selfconsistent nuclear calculations

The shell structure of superheavy nuclei is investigated within various parametrizations of relativistic and nonrelativistic nuclear mean field models. The heaviest known even-even nucleus 264Hs is used as a benchmark to estimate the predictive value of the models. From that starting point, doubly magic spherical nuclei are searched in the region Z=110-140 and N=134-298. They are found at (Z=114, N=184), (Z=120, N=172), or at (Z=126, N=184), depending on the parametrization.Comment: 16 pages RevTeX, 2 tables, 2 low resolution Gif figures (high resolution PostScript versions are available at http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html or at ftp://th.physik.uni-frankfurt.de/pub/bender ), submitted to Phys. Rev.