19,162 research outputs found

    The Tensor Current Divergence Equation in U(1) Gauge Theories is Free of Anomalies

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    The possible anomaly of the tensor current divergence equation in U(1) gauge theories is calculated by means of perturbative method. It is found that the tensor current divergence equation is free of anomalies.Comment: Revtex4, 7 pages, 2 figure

    Ions in solution: Density Corrected Density Functional Theory (DC-DFT)

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    Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HO\cdotCl^- and HO\cdotH2_2O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent

    Top quark forward-backward asymmetry and charge asymmetry in left-right twin Higgs model

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    In order to explain the Tevatron anomaly of the top quark forward-backward asymmetry AFBtA_{FB}^t in the left-right twin Higgs model, we choose to give up the lightest neutral particle of h^\hat{h} field as a stable dark matter candidate. Then a new Yukawa interaction for h^\hat{h} is allowed, which can be free from the constraint of same-sign top pair production and contribute sizably to AFBtA_{FB}^t. Considering the constraints from the production rates of the top pair (ttˉt\bar t), the top decay rates and ttˉt\bar{t} invariant mass distribution, we find that this model with such new Yukawa interaction can explain AFBtA_{FB}^t measured at the Tevatron while satisfying the charge asymmetry ACtA_{C}^t measured at the LHC.Moreover, this model predicts a strongly correlation between ACtA_{C}^t at the LHC and AFBtA_{FB}^t at the Tevatron, i.e., ACtA_{C}^t increases as AFBtA_{FB}^t increases.Comment: 17 pages, 9 figures; matches the published versio

    SPEAR Far Ultraviolet Spectral Images of the Cygnus Loop

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    We present far-ultraviolet (FUV) spectral images, measured at C IV 1550, He II 1640, Si IV+O IV] 1400, and O III] 1664, of the entire Cygnus Loop, observed with the Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR) instrument, also known as FIMS. The spatial distribution of FUV emission generally corresponds with a limb-brightened shell, and is similar to optical, radio and X-ray images. The features found in the present work include a ``carrot'', diffuse interior, and breakout features, which have not been seen in previous FUV studies. Shock velocities of 140-160 km/s is found from a line ratio of O IV] to O III], which is insensitive not only to resonance scattering but also to elemental abundance. The estimated velocity indicates that the fast shocks are widespread across the remnant. By comparing various line ratios with steady-state shock models, it is also shown that the resonance scattering is widespread.Comment: 13 pages, 3 figures, 1 table, accepted for publication in ApJ

    Effects of Line-tying on Resistive Tearing Instability in Slab Geometry

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    The effects of line-tying on resistive tearing instability in slab geometry is studied within the framework of reduced magnetohydrodynamics (RMHD).\citep{KadomtsevP1974,Strauss1976} It is found that line-tying has a stabilizing effect. The tearing mode is stabilized when the system length LL is shorter than a critical length LcL_{c}, which is independent of the resistivity η\eta. When LL is not too much longer than LcL_{c}, the growthrate γ\gamma is proportional to η\eta . When LL is sufficiently long, the tearing mode scaling γη3/5\gamma\sim\eta^{3/5} is recovered. The transition from γη\gamma\sim\eta to γη3/5\gamma\sim\eta^{3/5} occurs at a transition length Ltη2/5L_{t}\sim\eta^{-2/5}.Comment: Correct a typ

    The black hole fundamental plane from a uniform sample of radio and X-ray emitting broad line AGNs

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    We derived the black hole fundamental plane relationship among the 1.4GHz radio luminosity (L_r), 0.1-2.4keV X-ray luminosity (L_X), and black hole mass (M) from a uniform broad line SDSS AGN sample including both radio loud and radio quiet X-ray emitting sources. We found in our sample that the fundamental plane relation has a very weak dependence on the black hole mass, and a tight correlation also exists between the Eddington luminosity scaled X-ray and radio luminosities for the radio quiet subsample. Additionally, we noticed that the radio quiet and radio loud AGNs have different power-law slopes in the radio--X-ray non-linear relationship. The radio loud sample displays a slope of 1.39, which seems consistent with the jet dominated X-ray model. However, it may also be partly due to the relativistic beaming effect. For radio quiet sample the slope of the radio--X-ray relationship is about 0.85, which is possibly consistent with the theoretical prediction from the accretion flow dominated X-ray model. We briefly discuss the reason why our derived relationship is different from some previous works and expect the future spectral studies in radio and X-ray bands on individual sources in our sample to confirm our result.Comment: 23 pages, 7 figures, ApJ accepte

    Entangling two superconducting LC coherent modes via a superconducting flux qubit

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    Based on a pure solid-state device consisting of two superconducting LC circuits coupled to a superconducting flux qubit, we propose in this paper that the maximally entangled coherent states of the two LC modes can be generated for arbitrary coherent states through flux qubit controls.Comment: 5 pages, 2 figure

    Visualizing the meaning of texts

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    We implemented SmartINFO, an experimental system for the visualization of the meaning of texts. SmartINFO consists of 4 modules: a universal grammar engine (UGE), an anaphora engine, a concept engine and a visualization engine. We discuss two methods of visualizing meanings of text. One approach is a word-centered approach and the other, a clausal-centered approach. © 2005 IEEE
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