85,104 research outputs found

    Signatures of Technicolor Models with the GIM Mechanism

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    We investigate the production and the decays of pseudo-Goldstone bosons (PGBs) predicted by technicolor theories with the GIM mechanism (TC-GIM). The TC-GIM models contain exotic fermion families that do not interact under weak SU(2)SU(2), but they do have color and hypercharge interactions. These fermions form PGBs, which are the lightest exotic particles in the TC-GIM models. The spectrum of PGBs consists of color octets, leptoquarks and neutral particles. The masses of leptoquarks and color octets depend on a free parameter - the scale of confining interactions. Characteristic for TC-GIM models is a very light (approx 1 GeV) neutral particle with anomalous couplings to gauge boson pairs. We show how current experiments constrain the free parameters of the models. The best tests are provided by the pp --> TT and e^+e^- --> P^0 gamma reactions. Experiments at LHC and NLC can find PGBs of TC-GIM models in a wide range of parameter space. However, TC-GIM models can be distinguished from other TC models only if several PGBs are discovered.Comment: 31 pages, LaTeX, 9 embedded figure

    Development of the general interpolants method for the CYBER 200 series of supercomputers

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    The General Interpolants Method (GIM) is a 3-D, time-dependent, hybrid procedure for generating numerical analogs of the conservation laws. This study is directed toward the development and application of the GIM computer code for fluid dynamic research applications as implemented for the Cyber 200 series of supercomputers. An elliptic and quasi-parabolic version of the GIM code are discussed. Turbulence models, algebraic and differential equations, were added to the basic viscous code. An equilibrium reacting chemistry model and an implicit finite difference scheme are also included

    Development and application of the GIM code for the Cyber 203 computer

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    The GIM computer code for fluid dynamics research was developed. Enhancement of the computer code, implicit algorithm development, turbulence model implementation, chemistry model development, interactive input module coding and wing/body flowfield computation are described. The GIM quasi-parabolic code development was completed, and the code used to compute a number of example cases. Turbulence models, algebraic and differential equations, were added to the basic viscous code. An equilibrium reacting chemistry model and implicit finite difference scheme were also added. Development was completed on the interactive module for generating the input data for GIM. Solutions for inviscid hypersonic flow over a wing/body configuration are also presented

    Computation of three-dimensional nozzle-exhaust flow fields with the GIM code

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    A methodology is introduced for constructing numerical analogs of the partial differential equations of continuum mechanics. A general formulation is provided which permits classical finite element and many of the finite difference methods to be derived directly. The approach, termed the General Interpolants Method (GIM), can combined the best features of finite element and finite difference methods. A quasi-variational procedure is used to formulate the element equations, to introduce boundary conditions into the method and to provide a natural assembly sequence. A derivation is given in terms of general interpolation functions from this procedure. Example computations for transonic and supersonic flows in two and three dimensions are given to illustrate the utility of GIM. A three-dimensional nozzle-exhaust flow field is solved including interaction with the freestream and a coupled treatment of the shear layer. Potential applications of the GIM code to a variety of computational fluid dynamics problems is then discussed in terms of existing capability or by extension of the methodology

    The GIM Mechanism: origin, predictions and recent uses

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    The GIM Mechanism was introduced by Sheldon L. Glashow, John Iliopoulos and Luciano Maiani in 1970, to explain the suppression of Delta S=1, 2 neutral current processes and is an important element of the unified theories of the weak and electromagnetic interactions. Origin, predictions and uses of the GIM Mechanism are illustrated. Flavor changing neutral current processes (FCNC) represent today an important benchmark for the Standard Theory and give strong limitations to theories that go beyond ST in the few TeV region. Ideas on the ways constraints on FCNC may be imposed are briefly described.Comment: Opening Talk, Rencontres de Moriond, EW Interactions and Unified Theories, La Thuile, Valle d'Aosta, Italia, 2-9 March, 201

    Thrust chamber performance using Navier-Stokes solution

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    The viscous, axisymmetric flow in the thrust chamber of the space shuttle main engine (SSME) was computed on the CRAY 205 computer using the general interpolants method (GIM) code. Results show that the Navier-Stokes codes can be used for these flows to study trends and viscous effects as well as determine flow patterns; but further research and development is needed before they can be used as production tools for nozzle performance calculations. The GIM formulation, numerical scheme, and computer code are described. The actual SSME nozzle computation showing grid points, flow contours, and flow parameter plots is discussed. The computer system and run times/costs are detailed

    Finite difference grid generation by multivariate blending function interpolation

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    The General Interpolants Method (GIM) code which solves the multidimensional Navier-Stokes equations for arbitrary geometric domains is described. The geometry module in the GIM code generates two and three dimensional grids over specified flow regimes, establishes boundary condition information and computes finite difference analogs for use in the GIM code numerical solution module. The technique can be classified as an algebraic equation approach. The geometry package uses multivariate blending function interpolation of vector-values functions which define the shapes of the edges and surfaces bounding the flow domain. By employing blending functions which conform to the cardinality conditions the flow domain may be mapped onto a unit square (2-D) or unit cube (3-D), thus producing an intrinsic coordinate system for the region of interest. The intrinsic coordinate system facilitates grid spacing control to allow for optimum distribution of nodes in the flow domain

    Flavor-Changing Magnetic Dipole Moment and Oscillation of a Neutrino in a Degenerate Electron Plasma

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    The standard model prediction for a magnetic dipole moment of a neutrino is proportional to the neutrino mass and extremely small. It also generates a flavor-changing process, but the GIM mechanism reduces the corresponding amplitude. These properties of a neutrino magnetic moment change drastically in a degenerate electron plasma. We have shown that an electron-hole excitation gives a contribution proportional to the electrons' Fermi momentum. Since this effect is absent in μ\mu and τ\tau sector, the GIM cancellation does not work. The magnetic moment induces a neutrino oscillation if a strong enough magnetic field exists in the plasma. The required magnitude of the field strength that affects the \nue\ burst from a supernova is estimated to be the order of 10810^8 Gauss.Comment: 10 pages, Latex, Misleading terminology and typographical errors are correcte

    Straightening out the concept of direct and indirect input requirements

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    Gim & Kim (1998) proposed a generalization of Jeong (1982, 1984) reinterpretation of the Hawkins-Simon condition for macroeconomic stability to off-diagonal matrix elements. This generalization is conceptually relevant for it offers a complementary view of interindustry linkages beyond final or net output influence. The extension is completely similar to the 'total flow' idea introduced by Szyrmer (1992) or the 'output-to-output' multiplier of Miller & Blair (2009). However the practical implementation of Gim & Kim is actually faulty since it confuses the appropriate order of output normalization. We provide a new and elementary solution for the correct formalization using standard interindustry accounting concepts.output multipliers, input multipliers, Leontief multipliers.
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