5,760 research outputs found

    Twining characters and orbit Lie algebras

    Full text link
    We associate to outer automorphisms of generalized Kac-Moody algebras generalized character-valued indices, the twining characters. A character formula for twining characters is derived which shows that they coincide with the ordinary characters of some other generalized Kac-Moody algebra, the so-called orbit Lie algebra. Some applications to problems in conformal field theory, algebraic geometry and the theory of sporadic simple groups are sketched.Comment: 6 pages, LaTeX, Talk given by C. Schweigert at the XXI international colloquium on group theoretical methods in physics, July 1996, Goslar, German

    Understanding the bulk electronic structure of Ca1-xSrxVO3

    Full text link
    We investigate the electronic structure of Ca1-xSrxVO3 using careful state-of-the-art experiments and calculations. Photoemission spectra using synchrotron radiation reveal a hitherto unnoticed polarization dependence of the photoemission matrix elements for the surface component leading to a substantial suppression of its intensity. Bulk spectra extracted with the help of experimentally determined electron escape depth and estimated suppression of surface contributions resolve outstanding puzzles concerning the electronic structure in Ca1-xSrxVO3.Comment: 4 pages including 3 figure

    Physical properties of the jet from DG Tauri on sub-arcsecond scales with HST/STIS

    Full text link
    We derive the physical properties at the base of the jet from DG Tau both along and across the flow and as a function of velocity. We analysed seven optical spectra of the DG Tau jet, taken with the Hubble Space Telescope Imaging Spectrograph. The spectra were obtained by placing a long-slit parallel to the jet axis and stepping it across the jet width. The resulting position-velocity diagrams in optical forbidden emission lines allowed access to plasma conditions via calculation of emission line ratios. We find at the base of the jet high electron density, nen_e \sim 105^5, and very low ionisation, xe0.020.05x_e \sim 0.02-0.05, which combine to give a total density up to nHn_H \sim 3 106^6. This analysis confirms previous reports of variations in plasma parameters along the jet, (i.e. decrease in density by several orders of magnitude, increase of xex_e from 0.05 to a plateau at 0.7 downstream at 2'' from the star). Furthermore, a spatial coincidence is revealed between sharp gradients in the total density and supersonic velocity jumps. This strongly suggests that the emission is caused by shock excitation. The position-velocity diagrams indicate the presence of both fast accelerating gas and slower, less collimated material. We derive the mass outflow rate, M˙j\dot{M}_j, in the blue-shifted lobe in different velocity channels, that contribute to a total of M˙j\dot{M}_j \sim 8 ±\pm 4 109^{-9} M_\odot yr1^{-1}. We estimate that a symmetric bipolar jet would transport at the low and intermediate velocities probed by rotation measurements, an angular momentum flux of L˙j\dot{L}_j \sim 2.9 ±\pm 1.5 106^{-6} M_\odot yr1^{-1} AU km s1^{-1}. The derived properties of the DG Tau jet are demonstrated to be consistent with magneto-centrifugal theory. However, non-stationary modelling is required in order to explain all of the features revealed at high resolution.Comment: 16 pages, 18 figure

    Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase-distribution

    Full text link
    We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of J/ψJ/\psi production (integrated and differential) stemming from c-cˉ\bar{c} pairs that are initially uncorrelated.Comment: contribution presented at SQM0

    Investigation of dynamic ground effect

    Get PDF
    An experimental investigation of dynamic ground effect was conducted in the Univ. of Kansas wind tunnel using delta wings of 60, 70, 75 deg sweep; the XB-70 wing; and the F-104A wing. Both static and dynamic tests were made. Test data were compared to other test data, including dynamic flight test data of the XB-70 and F-104A. Limited flow visualization test were conducted. A significant dynamic effect was found for highly swept delta wings

    Scenario of inflationary cosmology from the phenomenological Λ\Lambda models

    Full text link
    Choosing the three phenomenological models of the dynamical cosmological term Λ\Lambda, viz., Λ(a˙/a)2\Lambda \sim (\dot a/a)^2, Λa¨/a\Lambda \sim {\ddot a/a} and Λρ\Lambda \sim \rho where aa is the cosmic scale factor, it has been shown by the method of numerical analysis that the three models are equivalent for the flat Universe k=0k=0. The evolution plots for dynamical cosmological term Λ\Lambda vs. time tt and also the cosmic scale factor aa vs. tt are drawn here for k=0,+1k=0, +1. A qualitative analysis has been made from the plots which supports the idea of inflation and hence expanding Universe.Comment: 12 latex pages with 12 figures; Replaced with the revised version; Accepeted for `J. Non-lin. Frac. Phen. Sci. Engg.
    corecore