1,017 research outputs found

    Magnetism in Dense Quark Matter

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    We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.Comment: To appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

    WMAP constraint on the P-term inflationary model

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    In light of WMAP results, we examine the observational constraint on the P-term inflation. With the tunable parameter ff, P-term inflation contains richer physics than D-term and F-term inflationary models. We find the logarithmic derivative spectral index with n>1n>1 on large scales and n<1n<1 on small scales in agreement to observation. We obtained a reasonable range for the choice of the gauge coupling constant gg in order to meet the requirements of WMAP observation and the expected number of the e-foldings. Although tuning ff and gg we can have larger values for the logarithmic derivative of the spectral index, it is not possible to satisfy all observational requirements for both, the spectral index and its logarithmic derivative at the same time.Comment: 6 pages, double column, 13 figures included. Version appearing in the Physical Review

    On the resolution of cosmic coincidence problem and phantom crossing with triple interacting fluids

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    We here investigate a cosmological model in which three fluids interact with each other involving certain coupling parameters and energy exchange rates. The motivation of the problem stems from the puzzling `triple coincidence problem' which naively asks why the cosmic energy densities of matter, radiation and dark energy are almost of the same order of magnitude at the present time. In our model, we determine the conditions under triple interacting fluids will cross the phantom divide.Comment: 22 pages, 6 figures, to appear in Eur. Phys. J. C (2009

    Relationships between a roller and a dynamic pressure distribution in circular hydraulic jumps

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    We investigated numerically the relation between a roller and the pressure distribution to clarify the dynamics of the roller in circular hydraulic jumps. We found that a roller which characterizes a type II jump is associated with two high pressure regions after the jump, while a type I jump (without the roller) is associated with only one high pressure region. Our numerical results show that building up an appropriate pressure field is essential for a roller.Comment: 10 pages, 7 PS files. To appear in PR

    Interacting Ricci Dark Energy and its Statefinder Description

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    In this paper we have considered an interacting Ricci dark energy in flat FRW universe. We have reconstructed the Hubble's parameter under this interaction. Also, we have investigated the statefinder diagnostics. It has been revealed that the equation of state parameter behaves like quintessence in this interaction and from the statefinder diagnostics it has been concluded that the interacting Ricci dark energy interpolates between dust and Λ\LambdaCDM stages of the universe.Comment: 9 pages, 3 figure

    Holographic dual of the Standard Model on the throat

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    We apply recent techniques to construct geometries, based on local Calabi-Yau manifolds, leading to warped throats with 3-form fluxes in string theory, with interesting structure at their bottom. We provide their holographic dual description in terms of RG flows for gauge theories with almost conformal duality cascades and infrared confinement. We describe a model of a throat with D-branes at its bottom, realizing a 3-family Standard Model like chiral sector. We provide the explicit holographic dual gauge theory RG flow, and describe the appearance of the SM degrees of freedom after confinement. As a second application, we describe throats within throats, namely warped throats with discontinuous warp factor in different regions of the radial coordinate, and discuss possible model building applications.Comment: 46 pages, 21 figures, reference adde

    Fermionic partner of Quintessence field as candidate for dark matter

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    Quintessence is a possible candidate for dark energy. In this paper we study the phenomenologies of the fermionic partner of Quintessence, the Quintessino. Our results show that, for suitable choices of the model parameters, the Quintessino is a good candidate for cold or warm dark matter. In our scenario, dark energy and dark matter of the Universe are connected in one chiral superfield.Comment: 4 pages, 3 figures, version to appear in PR

    The relationship between 100Cr6 steelmaking, inclusion microstructure and rolling contact fatigue performance

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    A processing-microstructure-performance approach is followed to study three bearing steel samples manufactured from the most frequently used continuous casting routes. The inclusion microstructures of the samples were altered by varying the metallurgy and hot working conditions. Inclusion size distribution information is obtained, showing the steel-making route that results in the highest cleanliness. 3D analysis of inclusion morphologies using electrolytic extraction indicates the irregularities on the surface to be favourable sites for crack nucleation under RCF. Flat-washer and ball-on-rod tests were conducted to study the rolling contact fatigue life of the steels, with the results from the flat-washer testing method being more representative for bearing life. This research suggests that early fatigue of bearings is governed by silicate fragmentation and late fatigue by TiN inclusions

    Parameterization and Reconstruction of Quasi Static Universe

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    We study a possibility of the fate of universe, in which there is neither the rip singularity, which results in the disintegration of bound systems, nor the endless expansion, instead the universe will be quasi static. We discuss the parameterization of the corresponding evolution and the reconstruction of the scalar field model. We find, with the parameterization consistent with the current observation, that the current universe might arrive at a quasi static phase after less than 20Gyr.Comment: minor changes and Refs. added, publish in EPJ

    2D and 3D Polar Plume Analysis from the Three Vantage Positions of STEREO/EUVI A, B, and SOHO/EIT

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    Polar plumes are seen as elongated objects starting at the solar polar regions. Here, we analyze these objects from a sequence of images taken simultaneously by the three spacecraft telescopes STEREO/EUVI A and B, and SOHO/EIT. We establish a method capable of automatically identifying plumes in solar EUV images close to the limb at 1.01 - 1.39 R in order to study their temporal evolution. This plume-identification method is based on a multiscale Hough-wavelet analysis. Then two methods to determined their 3D localization and structure are discussed: First, tomography using the filtered back-projection and including the differential rotation of the Sun and, secondly, conventional stereoscopic triangulation. We show that tomography and stereoscopy are complementary to study polar plumes. We also show that this systematic 2D identification and the proposed methods of 3D reconstruction are well suited, on one hand, to identify plumes individually and on the other hand, to analyze the distribution of plumes and inter-plume regions. Finally, the results are discussed focusing on the plume position with their cross-section area.Comment: 22 pages, 10 figures, Solar Physics articl
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