Nonperturbative Effective Actions of N=2 Supersymmetric Gauge Theories

We elaborate on our previous work on N=2 supersymmetric Yang-Mills theory. In particular, we show how to explicitly determine the low energy quantum effective action for $G=SU(3)$ from the underlying hyperelliptic Riemann surface, and calculate the leading instanton corrections. This is done by solving Picard-Fuchs equations and asymptotically evaluating period integrals. We find that the dynamics of the $SU(3)$ theory is governed by an Appell system of type $F_4$, and compute the exact quantum gauge coupling explicitly in terms of Appell functions.Comment: 57p, harvmac with hyperlinks, 9 uuencoded ps figure

On the Monodromies of N=2 Supersymmetric Yang-Mills Theory

We review the generalization of the work of Seiberg and Witten on N=2 supersymmetric SU(2) Yang-Mills theory to SU(n) gauge groups. The quantum moduli spaces of the effective low energy theory parametrize a special family of hyperelliptic genus n-1 Riemann surfaces. We discuss the massless spectrum and the monodromies.Comment: 15p, harvmac/lanlmac with hyperlinks, 4 uuencoded compressed postscript figures appende

Three-dimensional massive gravity and the bigravity black hole

We study three-dimensional massive gravity formulated as a theory with two dynamical metrics, like the f-g theories of Isham-Salam and Strathdee. The action is parity preserving and has no higher derivative terms. The spectrum contains a single massive graviton. This theory has several features discussed recently in TMG and NMG. We find warped black holes, a critical point, and generalized Brown-Henneaux boundary conditions.Comment: 8 pages, Revtex. Minor change. References adde

Simple Singularities and N=2 Supersymmetric Yang-Mills Theory

We present a first step towards generalizing the work of Seiberg and Witten on N=2 supersymmetric Yang-Mills theory to arbitrary gauge groups. Specifically, we propose a particular sequence of hyperelliptic genus $n-1$ Riemann surfaces to underly the quantum moduli space of $SU(n)$ N=2 supersymmetric gauge theory. These curves have an obvious generalization to arbitrary simply laced gauge groups, which involves the A-D-E type simple singularities. To support our proposal, we argue that the monodromy in the semiclassical regime is correctly reproduced. We also give some remarks on a possible relation to string theory.Comment: 13p, harvmac/lanlmac with hyperlinks 1 uuencoded PostScript figure appended (Some inconsistencies and typos were corrected, we also dropped our conjectures for the monodromies at strong coupling, of which we know now that they are different.

Development of high-strength corrosion-resistant austenitic TWIP steel

Based on thermodynamic calculations a (C+N) TWIP steel with the nominal compositionFe-25Mn-12Cr-0.3C-0.4N was developed and produced. Casting, diffusion annealing, hot rolling and waterquenching were performed leading to a fully austenitic structure without ?-ferrite or ?-martensite.Unidirectional tensile tests were performed, revealing a yield strength of 460 MPa, ultimate tensile strengthof 880 MPa (1700 MPa true strength) and an engineering strain of up to 100% at room temperature.The plasticity mechanisms were analysed based on the results of the tensile tests and cold work hardeningbehaviour, accompanied by microstructural analyses on deformed samples using X-Ray diffraction. Twinningwas found to be an important deformation mechanism, while martensitic transformations do not take place inthese materials. Correlation with predicted values of stacking fault energy (SFE) based on thermodynamicmodelling is also taken into account. Electrochemical corrosion tests show a good extent of passivation in0.5 M H2SO4 electrolyte. The structure, mechanical properties and corrosion resistance are compared toconventional TWIP steels such as Fe-25Mn-3Al-3Si and Fe-22Mn-0.6C

Fission half-lives of super-heavy nuclei in a microscopic approach

A systematic study of 160 heavy and super-heavy nuclei is performed in the Hartree-Fock-Bogoliubov approach with the finite range and density dependent Gogny force with the D1S parameter set. We show calculations in several approximations: with axially symmetric and reflexion symmetric wave functions, with axially symmetric and non-reflexion symmetric wave functions and finally some representative examples with triaxial wave functions are also discussed. Relevant properties of the ground state and along the fission path are thoroughly analyzed. Fission barriers, Q$_\alpha$-factors and lifetimes with respect to fission and $\alpha$-decay as well as other observables are discussed. Larger configuration spaces and more general HFB wave functions as compared to previous studies provide a very good agreement with the experimental data.Comment: 26 pages, 15 figure