872 research outputs found

    Topological first-order solitons in a gauged CP(2)CP(2) model with the Maxwell-Chern-Simons action

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    We verify the existence of radially symmetric first-order solitons in a gauged CP(2)CP(2) scenario in which the dynamics of the Abelian gauge field is controlled by the Maxwell-Chern-Simons action. We implement the standard Bogomol'nyi-Prasad-Sommerfield (BPS) formalism, from which we obtain a well-defined lower bound for the corresponding energy (i.e. the Bogomol'nyi bound) and the first-order equations saturating it. We solve these first-order equations numerically by means of the finite-difference scheme, therefore obtaining regular solutions of the effective model, their energy being quantized according the winding number rotulating the final configurations, as expected. We depict the numerical solutions, whilst commenting on the main properties they engender.Comment: 8 pages, 9 figure

    Long beating wavelength in the Schwarz-Hora effect

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    Thirty years ago, H.Schwarz has attempted to modulate an electron beam with optical frequency. When a 50-keV electron beam crossed a thin crystalline dielectric film illuminated with laser light, electrons produced the electron-diffraction pattern not only at a fluorescent target but also at a nonfluorescent target. In the latter case the pattern was of the same color as the laser light (the Schwarz-Hora effect). This effect was discussed extensively in the early 1970s. However, since 1972 no reports on the results of further attempts to repeat those experiments in other groups have appeared, while the failures of the initial such attempts have been explained by Schwarz. The analysis of the literature shows there are several unresolved up to now contradictions between the theory and the Schwarz experiments. In this work we consider the interpretation of the long-wavelength spatial beating of the Schwarz-Hora radiation. A more accurate expression for the spatial period has been obtained, taking into account the mode structure of the laser field within the dielectric film. It is shown that the discrepancy of more than 10% between the experimental and theoretical results for the spatial period cannot be reduced by using the existing quantum models that consider a collimated electron beam.Comment: 3 pages, RevTe

    Isotropic to distortional hardening transition in metal plasticity

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    The present paper aims to discuss the transition from isotropic to distortional hardening behavior of metallic materials, based on the Homogeneous Anisotropic Hardening (HAH) model. Furthermore, the effect of yield locus distortion on the evolution of the strain increment, under the assumption of associated flow, is theoretically discussed and exemplified. Special cases, such as coaxial and orthogonal stress states, are analyzed to provide better insight into the model. Particular emphasis is put on the monotonic loading case, which is compared to isotropic hardening. Finally, the evolution equations of the state variables are examined and their properties are discussed. (C) 2014 Elsevier Ltd. All rights reserved.111512Ysciescopu

    A dual-mesh strategy for the 3d simulation of fineblanking processes

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    Fineblanking technology is used to produce blanked metal components which show outstanding surface quality and part flatness. The defining characteristics of the process are, besides the use of a counter punch and a V- Ring, the tiny die clearance and a rounded cutting edge. The 3D FE simulation of the process proves to be thus very challenging. This is mainly because in comparison to the part dimensions (which are of the order of 10mm) a very small mesh size needs to be chosen on the cutting edge (~0.01mm), which leads to a very big number of elements and also tiny time steps. This paper aims to show a solution to the problem using the Arbitrary Lagrangian Eulerian FE formulation, applied on two different levels of refinement. First a relatively coarse mesh (element size of about 0.1mm around the cutting edge) is applied to solve the full size 3D problem. The flow information is subsequently used on a much finer mesh (size ~0.005) defined around a small region on the cutting line to accurately compute the stress-strain distribution around the radi

    Thermal Phase Variations of WASP-12b: Defying Predictions

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    [Abridged] We report Warm Spitzer full-orbit phase observations of WASP-12b at 3.6 and 4.5 micron. We are able to measure the transit depths, eclipse depths, thermal and ellipsoidal phase variations at both wavelengths. The large amplitude phase variations, combined with the planet's previously-measured day-side spectral energy distribution, is indicative of non-zero Bond albedo and very poor day-night heat redistribution. The transit depths in the mid-infrared indicate that the atmospheric opacity is greater at 3.6 than at 4.5 micron, in disagreement with model predictions, irrespective of C/O ratio. The secondary eclipse depths are consistent with previous studies. We do not detect ellipsoidal variations at 3.6 micron, but our parameter uncertainties -estimated via prayer-bead Monte Carlo- keep this non-detection consistent with model predictions. At 4.5 micron, on the other hand, we detect ellipsoidal variations that are much stronger than predicted. If interpreted as a geometric effect due to the planet's elongated shape, these variations imply a 3:2 ratio for the planet's longest:shortest axes and a relatively bright day-night terminator. If we instead presume that the 4.5 micron ellipsoidal variations are due to uncorrected systematic noise and we fix the amplitude of the variations to zero, the best fit 4.5 micron transit depth becomes commensurate with the 3.6 micron depth, within the uncertainties. The relative transit depths are then consistent with a Solar composition and short scale height at the terminator. Assuming zero ellipsoidal variations also yields a much deeper 4.5 micron eclipse depth, consistent with a Solar composition and modest temperature inversion. We suggest future observations that could distinguish between these two scenarios.Comment: 19 pages, 10 figures, ApJ in press. Improved discussion of gravity brightenin

    Radial Bargmann representation for the Fock space of type B

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    Let να,q\nu_{\alpha,q} be the probability and orthogonality measure for the qq-Meixner-Pollaczek orthogonal polynomials, which has appeared in \cite{BEH15} as the distribution of the (α,q)(\alpha,q)-Gaussian process (the Gaussian process of type B) over the (α,q)(\alpha,q)-Fock space (the Fock space of type B). The main purpose of this paper is to find the radial Bargmann representation of να,q\nu_{\alpha,q}. Our main results cover not only the representation of qq-Gaussian distribution by \cite{LM95}, but also of q2q^2-Gaussian and symmetric free Meixner distributions on R\mathbb R. In addition, non-trivial commutation relations satisfied by (α,q)(\alpha,q)-operators are presented.Comment: 13 pages, minor changes have been mad

    Compactlike kinks and vortices in generalized models

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    This work deals with the presence of topological defects in k-field models, where the dynamics is generalized to include higher order power in the kinetic term. We investigate kinks in (1,1) dimensions and vortices in (2,1) dimensions, focusing on some specific features of the solutions. In particular, we show how the kinks and vortices change to compactlike solutions, controlled by the parameter used to introduce the generalized models.Comment: 7 pages, 7 figures. Version to be published in PR

    Generalized self-dual Maxwell-Chern-Simons-Higgs model

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    We present a consistent BPS framework for a generalized Maxwell-Chern-Simons-Higgs model. The overall model, including its self-dual potential, depends on three different functions, h(|{\phi}|,N), w(|{\phi}|) and G(|{\phi}|), which are functions of the scalar fields only. The BPS energy is proportional to the magnetic flux when w(|{\phi}|) and G(|{\phi}|) are related to each other by a differential constraint. We present an explicit non-standard model and its topologically non-trivial static configurations, which are described by the usual radially symmetric profile. Finally, we note that the non-standard results behave in a similar way as their standard counterparts, as expected, reinforcing the consistence of the overall construction.Comment: 6 pages, 5 figure

    The Infrared Array Camera Dark Field: Far-Infrared to X-ray Data

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    We present 20 band photometry from the far-IR to X-ray in the Spitzer Infrared Array Camera (IRAC) dark field. The bias for the near-IR camera on Spitzer is calibrated by observing a ~20' diameter "dark" field near the north ecliptic pole roughly every two-to-three weeks throughout the mission duration of Spitzer. The field is unique for its extreme depth, low background, high quality imaging, time-series information, and accompanying photometry including data taken with Akari, Palomar, MMT, KPNO, Hubble, and Chandra. This serendipitous survey contains the deepest mid-IR data taken to date. This data set is well suited for studies of intermediate-redshift galaxy clusters, high-redshift galaxies, the first generation of stars, and the lowest mass brown dwarfs, among others. This paper provides a summary of the data characteristics and catalog generation from all bands collected to date as well as a discussion of photometric redshifts and initial and expected science results and goals. To illustrate the scientific potential of this unique data set, we also present here IRAC color-color diagrams

    Avalanche boron fusion by laser picosecond block ignition with magnetic trapping for clean and economic reactor

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    After the very long consideration of the ideal energy source by fusion of the protons of light hydrogen with the boron isotope 11 (boron fusion HB11) the very first two independent measurements of very high reaction gains by lasers basically opens a fundamental breakthrough. The non-thermal plasma block ignition with extremely high power laser pulses above petawatt of picosecond duration in combination with up to ten kilotesla magnetic fields for trapping has to be combined to use the measured high gains as proof of an avalanche reaction for an environmentally clean, low cost and lasting energy source as potential option against global warming. The unique HB11 avalanche reaction is are now based on elastic collisions of helium nuclei (alpha particles) limited only to a reactor for controlled fusion energy during a very short time within a very small volume.Comment: 11 pages, 6 figures, Submitted to Proceedings 2nd Symposium High Power Laser Science and Engineering, 14-18 MARCH 2016, Suzhou/Chin
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