Mott--Hubbard transition vs. Anderson localization of correlated, disordered electrons

The phase diagram of correlated, disordered electrons is calculated within dynamical mean--field theory using the geometrically averaged (''typical'') local density of states. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are identified. The Mott and Anderson insulators are found to be continuously connected.Comment: 4 pages, 4 figure

Generalized Quantum Theory: Overview and Latest Developments

The main formal structures of Generalized Quantum Theory are summarized. Recent progress has sharpened some of the concepts, in particular the notion of an observable, the action of an observable on states (putting more emphasis on the role of proposition observables), and the concept of generalized entanglement. Furthermore, the active role of the observer in the structure of observables and the partitioning of systems is emphasized.Comment: 14 pages, update in reference

Gregorius: A Medieval Oedipus Legend

Originally published in 1955, this rendering in rhyming couplets was the first English translation to appear of the medieval Oedipus legend of Gregorius, made known to readers by Thomas Mann in his novel "The Holy Sinner" (1951). The introduction situates Hartmann's poem in the pantheon of Gregorius legends by writers from Sophocles to Mann

Implications of the Broad 26A1 1809 keV Line Observed by GRIS

The surprisingly large width of the 1809 ke V gamma-ray line from decay old radioactive Al, recently observed by GRIS (Naya et al. 1996), has profound astrophysical implications. While there may be no apparent, single mechanism that can explain the oberved broadening, wen identify high speed dust grains, extremely hot superbubbles, and a large, low density, gaseous halo in the Galactic center region as the possible origins and iscuss their intriguing revelation of the hot gas content in the ISM

Persistent Current in the Ferromagnetic Kondo Lattice Model

In this paper, we study the zero temperature persistent current in a ferromagnetic Kondo lattice model in the strong coupling limit. In this model, there are spontaneous spin textures at some values of the external magnetic flux. These spin textures contribute a geometric flux, which can induce an additional spontaneous persistent current. Since this spin texture changes with the external magnetic flux, we find that there is an anomalous persistent current in some region of magnetic flux: near Phi/Phi_0=0 for an even number of electrons and Phi/Phi_0=1/2 for an odd number of electrons.Comment: 6 RevTeX pages, 10 figures include

The Dynamic X-Ray Sky of the Local Universe

Over the next decade, we can expect time domain astronomy to flourish at optical and radio wavelengths. In parallel with these efforts, a dedicated transient machine operating at higher energies (X-ray band through soft gamma-rays) is required to reveal the unique subset of events with variable emission predominantly visible above 100 eV. Here we focus on the transient phase space never yet sampled due to the lack of a sensitive, wide-field and triggering facility dedicated exclusively to catching high energy transients and enabling rapid coordinated multi-wavelength follow-up. We first describe the advancements in our understanding of known X-ray transients that can only be enabled through such a facility and then focus on the classes of transients theoretically predicted to be out of reach of current detection capabilities. Finally there is the exciting opportunity of revealing new classes of X-ray transients and unveiling their nature through coordinated follow-up observations at longer wavelengths

Monte Carlo Simulations for the Magnetic Phase Diagram of the Double Exchange Hamiltonian

We have used Monte Carlo simulation techniques to obtain the magnetic phase diagram of the double exchange Hamiltonian. We have found that the Berry's phase of the hopping amplitude has a negligible effect in the value of the magnetic critical temperature. To avoid finite size problems in our simulations we have also developed an approximated expression for the double exchange energy. This allows us to obtain the critical temperature for the ferromagnetic to paramagnetic transition more accurately. In our calculations we do not observe any strange behavior in the kinetic energy, chemical potential or electron density of states near the magnetic critical temperature. Therefore, we conclude that other effects, not included in the double exchange Hamiltonian, are needed to understand the metal-insulator transition which occurs in the manganites.Comment: 6 pages Revtex, 8 PS figure