24,269 research outputs found

    Quantum Fermion Hair

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    It is shown that the Dirac operator in the background of a magnetic %Reissner-Nordstr\"om black hole and a Euclidean vortex possesses normalizable zero modes in theories containing superconducting cosmic strings. One consequence of these zero modes is the presence of a fermion condensate around magnetically charged black holes which violates global quantum numbers.Comment: 16pp (harvmac (l)) and 2 figs.(not included

    Ultraviolet Properties of the Higgs Sector in the Lee-Wick Standard Model

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    The Lee-Wick (LW) Standard Model (SM) offers a new solution to the hierarchy problem. We discuss, using effective potential techniques, its peculiar ultraviolet (UV) behaviour. We show how quadratic divergences in the Higgs mass Mh cancel as a result of the unusual dependence of LW fields on the Higgs background (in a manner reminiscent of Little Higgses). We then extract from the effective potential the renormalization group evolution of the Higgs quartic coupling lambda above the LW scale. After clarifying an apparent discrepancy with previous results for the LW Abelian Higgs model we focus on the LWSM. In contrast with the SM case, for any Mh, lambda grows monotonically and hits a Landau pole at a fixed trans-Planckian scale (never turning negative in the UV). Then, the perturbativity and stability bounds on Mh disappear. We identify a cutoff ~10^{16} GeV for the LWSM due to the hypercharge gauge coupling hitting a Landau pole. Finally, we also discuss briefly the possible impact of the UV properties of the LW models on their behaviour at finite temperature, in particular regarding symmetry nonrestoration.Comment: 25 pages, 3 figure

    The analysis of temporal variations in regional models of the Sargasso Sea from GEOS-3 altimetry

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    The dense coverage of short pulse mode GEOS-3 altimeter data in the western North Atlantic provides a basis for studying time variations in the sea surface heights in the Sargasso Sea. Two techniques are utilized: the method of regional models, and the analysis of overlapping passes. An 88 percent correlation is obtained between the location of cyclonic eddies obtained from infrared imagery and sea surface height minima in the altimeter models. This figure drops to 59 percent in the case of correlations with maxima and minima of surface temperature fields. The analysis of overlapping passes provides a better picture of instantaneous sea state through wavelengths greater than 30 km. The variability of the Sargasso Sea through wavelengths between 150 km and 5000 km is estimated at + or - 28 cm. This value is in reasonable agreement with oceanographic estimates and is compatible with the eddy kinetic energy of a wind driven circulation

    Factors Affecting Trade in Mexican Imports of Poultry Meat from the United States

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    U.S. exports of poultry to Mexico have increased steadily since NAFTA came into force in January 1994. The Mexican poultry industry has become increasingly concerned about these exports, arguing that it cannot compete with U.S. products. The Mexicans argue that U.S. poultry exports to Mexico are duty free under NAFTA (as of January 1, 2003). The Mexican industry also argues that U.S. poultry benefits from low-priced feed resulting from U.S. Government farm programs. We analyzed the impact of tariffs and U.S. feed grain programs on U.S. exports of poultry, and find that other factors appear to be more important in explaining trade. Specifically, Mexican preferences for dark meat provide large price incentives for U.S. exporters, while Mexican Government policies in support of its grain sector penalize poultry producers in Mexico.International Relations/Trade,

    Fate of the false monopoles: induced vacuum decay

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    We study a gauge theory model where there is an intermediate symmetry breaking to a meta- stable vacuum that breaks a simple gauge group to a U (1) factor. Such models admit the existence of meta-stable magnetic monopoles, which we dub false monopoles. We prove the existence of these monopoles in the thin wall approximation. We determine the instantons for the collective coordinate that corresponds to the radius of the monopole wall and we calculate the semi-classical tunneling rate for the decay of these monopoles. The monopole decay consequently triggers the decay of the false vacuum. As the monopole mass is increased, we find an enhanced rate of decay of the false vacuum relative to the celebrated homogeneous tunneling rate due to Coleman [1].Comment: 10 pages, 4 figure

    Baryon Asymmetry in a Heavy Moduli Scenario

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    In some models of supersymmetry breaking, modulus fields are heavy enough to decay before BBN. But the large entropy produced via moduli decay significantly dilutes the preexisting baryon asymmetry of the universe. We study whether Affleck-Dine mechanism can provide enough baryon asymmetry which survives the dilution, and find several situations in which desirable amount of baryon number remains after the dilution. The possibility of non-thermal dark matter is also discussed. This provides the realistic cosmological scenario with heavy moduli.Comment: 36 pages, 5 figures; added a reference; v3: minor correction

    Scaling tests with dynamical overlap and rooted staggered fermions

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    We present a scaling analysis in the 1-flavor Schwinger model with the full overlap and the rooted staggered determinant. In the latter case the chiral and continuum limit of the scalar condensate do not commute, while for overlap fermions they do. For the topological susceptibility a universal continuum limit is suggested, as is for the partition function and the Leutwyler-Smilga sum rule. In the heavy-quark force no difference is visible even at finite coupling. Finally, a direct comparison between the complete overlap and the rooted staggered determinant yields evidence that their ratio is constant up to O(a2)O(a^2) effects.Comment: 28 pages, 20 figures containg 37 graphs. v2: 6 new references, 2 new footnotes (to match published version

    Space Time Foam: a ground state candidate for Quantum Gravity

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    A model of space-time foam, made by NN wormholes is considered. The Casimir energy leading to such a model is computed by means of the phase shift method which is in agreement with the variational approach used in Refs.[9-14]. The collection of Schwarzschild and Reissner-Nordstr\"{o}m wormholes are separately considered to represent the foam. The Casimir energy shows that the Reissner-Nordstr\"{o}m wormholes cannot be used to represent the foam.Comment: 6 pages.RevTeX with package epsf and two eps figures. To be submitted to the proceedings of the 4th Workshop of `Mysteries, Puzzles And Paradoxes In Quantum Mechanics' Gargnano (Italy), 27 August-1 September 200
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