142,592 research outputs found

    Lagrangian approach to local symmetries and self-dual model in gauge invariant formulation

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    Taking the St\"uckelberg Lagrangian associated with the abelian self-dual model of P.K. Townsend et al as a starting point, we embed this mixed first- and second-class system into a pure first-class system by following systematically the generalized Hamiltonian approach of Batalin, Fradkin and Tyutin. The resulting Lagrangian possesses an extended gauge invariance and provides a non-trivial example for a general Lagrangian approach to unravelling the full set of local symmetries of a Lagrangian.Comment: LaTeX, 15 page

    Generalized BFT Formalism of Electroweak Theory in the Unitary Gauge

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    We systematically embed the SU(2)×\timesU(1) Higgs model in the unitary gauge into a fully gauge-invariant theory by following the generalized BFT formalism. We also suggest a novel path to get a first-class Lagrangian directly from the original second-class one using the BFT fields.Comment: 14 pages, Latex, no figure

    Phase Transitions in the Early Universe

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    The physics of the 20th Century is governed by two pillars, Einstein's relativity principle and the quantum principle. At the beginning of the 21st Century, it becomes clear that there exist the smallest units of matter, such as electrons, neutrinos, and quarks; their behaviors are described by the Standard Model. It was believed that the temperature of the early Universe was once 300 GeV, or higher, at 10−11sec10^{-11} sec, and then going through the electroweak phase transition. But the mass phase transition happens in the purely imaginary temperature. Later on, its temperature was 150 MeV at 3.3×10−5sec3.3 \times 10^{-5} sec, and then going through the "QCD cosmological phase transition". We attempt to use the Standard Model, a completely dimensionless theory apart from the negative "ignition" term, to conclude that the EW or mass phase transition {\it does not exist}. On the front of QCD cosmological phase transition, the intriguing question about the latent heat (energy) is discussed and its role is speculated.Comment: 24 pages, 1 figur

    Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 7Li+208Pb System at Near-Coulomb-Barrier Energies using the Folding Potential

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    Simultaneous χ2\chi^{2} analyses previously made for elastic scattering and fusion cross section data for the 6^{6}Li+208^{208}Pb system is extended to the 7^{7}Li+208^{208}Pb system at near-Coulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the χ2\chi^{2} analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the Continuum Discretized Coupled Channel (CDCC) calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the 7^7Li+208^{208}Pb system with the analysis previously made for the 6^{6}Li+208^{208}Pb system.Comment: 7 figures, submitted to PR

    Magnetoresistance devices Progress report

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    Investigating galvanomagnetic effects in developing higher magnetoresistance devices for low voltage high current switche

    The effects of surface finish and grain size on the strength of sintered silicon carbide

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    The effects of surface treatment and microstructure, especially abnormal grain growth, on the strength of sintered SiC were studied. The surfaces of sintered SiC were treated with 400, 800 and 1200 grit diamond wheels. Grain growth was induced by increasing the sintering times at 2050 C. The beta to alpha transformation occurred during the sintering of beta-phase starting materials and was often accompanied by abnormal grain growth. The overall strength distributions were established using Weibull statistics. The strength of the sintered SiC is limited by extrinsic surface flaws in normal-sintered specimens. The finer the surface finish and grain size, the higher the strength. But the strength of abnormal sintering specimens is limited by the abnormally grown large tabular grains. The Weibull modulus increases with decreasing grain size and decreasing grit size for grinding
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