21,715 research outputs found

    Disclination in Lorentz Space-Time

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    The disclination in Lorentz space-time is studied in detail by means of topological properties of ϕ\phi -mapping. It is found the space-time disclination can be described in term of a Dirac spinor. The size of the disclination, which is proved to be the difference of two sets of su(2)% -like monopoles expressed by two mixed spinors, is quantized topologically in terms of topological invariants−-winding number. The projection of space-time disclination density along an antisymmetric tensor field is characterized by Brouwer degree and Hopf index.Comment: Revtex, 7 page

    Evolution of the Chern-Simons Vortices

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    Based on the gauge potential decomposition theory and the Ï•\phi -mapping theory, the topological inner structure of the Chern-Simons-Higgs vortex has been showed in detail. The evolution of CSH vortices is studied from the topological properties of the Higgs scalar field. The vortices are found generating or annihilating at the limit points and encountering, splitting or merging at the bifurcation points of the scalar field Ï•.\phi .Comment: 10 pages, 10 figure

    Topology of Knotted Optical Vortices

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    Optical vortices as topological objects exist ubiquitously in nature. In this paper, by making use of the Ï•\phi-mapping topological current theory, we investigate the topology in the closed and knotted optical vortices. The topological inner structure of the optical vortices are obtained, and the linking of the knotted optical vortices is also given.Comment: 11 pages, no figures, accepted by Commun. Theor. Phys. (Beijing, P. R. China

    Comment on "Quantum Phase Slips and Transport in Ultrathin Superconducting Wires"

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    In a recent Letter (Phys. Rev. Lett.78, 1552 (1997) ), Zaikin, Golubev, van Otterlo, and Zimanyi criticized the phenomenological time-dependent Ginzburg-Laudau model which I used to study the quantum phase-slippage rate for superconducting wires. They claimed that they developed a "microscopic" model, made qualitative improvement on my overestimate of the tunnelling barrier due to electromagnetic field. In this comment, I want to point out that, i), ZGVZ's result on EM barrier is expected in my paper; ii), their work is also phenomenological; iii), their renormalization scheme is fundamentally flawed; iv), they underestimated the barrier for ultrathin wires; v), their comparison with experiments is incorrect.Comment: Substantial changes made. Zaikin et al's main result was expected from my work. They underestimated tunneling barrier for ultrathin wires by one order of magnitude in the exponen

    Generalized Stable Multivariate Distribution and Anisotropic Dilations

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    After having closely re-examined the notion of a L\'evy's stable vector, it is shown that the notion of a stable multivariate distribution is more general than previously defined. Indeed, a more intrinsic vector definition is obtained with the help of non isotropic dilations and a related notion of generalized scale. In this framework, the components of a stable vector may not only have distinct Levy's stability indices α\alpha's, but the latter may depend on its norm. Indeed, we demonstrate that the Levy's stability index of a vector rather correspond to a linear application than to a scalar, and we show that the former should satisfy a simple spectral property

    Angular Momentum Conservation Law for Randall-Sundrum Models

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    In Randall-Sundrum models, by the use of general Noether theorem, the covariant angular momentum conservation law is obtained with the respect to the local Lorentz transformations. The angular momentum current has also superpotential and is therefore identically conserved. The space-like components JijJ_{ij} of the angular momentum for Randall-Sundrum models are zero. But the component J04J_{04} is infinite.Comment: 10 pages, no figures, accepted by Mod. Phys. Lett.

    A new topological aspect of the arbitrary dimensional topological defects

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    We present a new generalized topological current in terms of the order parameter field ϕ⃗\vec \phi to describe the arbitrary dimensional topological defects. By virtue of the % \phi-mapping method, we show that the topological defects are generated from the zero points of the order parameter field ϕ⃗\vec \phi, and the topological charges of these topological defects are topological quantized in terms of the Hopf indices and Brouwer degrees of ϕ\phi-mapping under the condition that the Jacobian % J(\frac \phi v)\neq 0. When J(ϕv)=0J(\frac \phi v)=0, it is shown that there exist the crucial case of branch process. Based on the implicit function theorem and the Taylor expansion, we detail the bifurcation of generalized topological current and find different directions of the bifurcation. The arbitrary dimensional topological defects are found splitting or merging at the degenerate point of field function ϕ⃗\vec \phi but the total charge of the topological defects is still unchanged.Comment: 24 pages, 10 figures, Revte

    Neutrino spin oscillations in gravitational fields

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    We study neutrino spin oscillations in black hole backgrounds. In the case of a charged black hole, the maximum frequency of oscillations is a monotonically increasing function of the charge. For a rotating black hole, the maximum frequency decreases with increasing the angular momentum. In both cases, the frequency of spin oscillations decreases as the distance from the black hole grows. As a phenomenological application of our results, we study simple bipolar neutrino system which is an interesting example of collective neutrino oscillations. We show that the precession frequency of the flavor pendulum as a function of the neutrino number density will be higher for a charged/non-rotating black hole compared with a neutral/rotating black hole respectively.Comment: Replaced with the version accepted for publication in Gravitation and Cosmology, Springer. 10 pages. 4 figure

    Topological Properties of Spatial Coherence Function

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    Topology of the spatial coherence function is considered in details. The phase singularity (coherence vortices) structures of coherence function are classified by Hopf index and Brouwer degree in topology. The coherence flux quantization and the linking of the closed coherence vortices are also studied from the topological properties of the spatial coherence function.Comment: 9 page
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