92,442 research outputs found

    The Stability of Noncommutative Scalar Solitons

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    We determine the stability conditions for a radially symmetric noncommutative scalar soliton at finite noncommutivity parameter θ\theta. We find an intriguing relationship between the stability and existence conditions for all level-1 solutions, in that they all have nearly-vanishing stability eigenvalues at critical θm2\theta m^2. The stability or non-stability of the system may then be determined entirely by the ϕ3\phi^3 coefficient in the potential. For higher-level solutions we find an ambiguity in extrapolating solutions to finite θ\theta which prevents us from making any general statements. For these stability may be determined by comparing the fluctuation eigenvalues to critical values which we calculate.Comment: 12 pages, corrected typo

    A Note on Cosmic (p,q,r) Strings

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    The spectrum of (p,q)(p,q) bound states of F- and D-strings has a distinctive square-root tension formula that is hoped to be a hallmark of fundamental cosmic strings. We point out that the Bogomol'nyi-Prasad-Sommerfield (BPS) bound for vortices in N=2{\cal N}=2 supersymmetric Abelian-Higgs models also takes the square-root form. In contrast to string theory, the most general supersymmetric field theoretic model allows for (p,q,r)(p,q,r) strings, with three classes of strings rather than two. Unfortunately, we find that there do not exist BPS solutions except in the trivial case. The issue of whether there exist non-BPS solutions which may closely resemble the square-root form is left as an open question.Comment: 4 pages; v2: references adde

    A hybrid computer program for the visual display of compensatory system model parameters

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    A hybrid computer identification program has been developed which determines and displays those parameter values of a model of the compensatory control system that existed over the last fifteen seconds of operation. These values are up-dated every 0.05 sec so that a visual display of the parameters appears to be continuous. Presently, a closed loop crossover model is being used as the compensatory system model with the parameters K and tau displayed, however, any suitable model could be used in its place

    Cosmic Superstring Scattering in Backgrounds

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    We generalize the calculation of cosmic superstring reconnection probability to non-trivial backgrounds. This is done by modeling cosmic strings as wound tachyon modes in the 0B theory, and the spacetime effective action is then used to couple this to background fields. Simple examples are given including trivial and warped compactifications. Generalization to (p,q)(p,q) strings is discussed.Comment: 12 pages, 2 figures; v2: references adde

    Feynman-Jackson integrals

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    We introduce perturbative Feynman integrals in the context of q-calculus generalizing the Gaussian q-integrals introduced by Diaz and Teruel. We provide analytic as well as combinatorial interpretations for the Feynman-Jackson integrals.Comment: Final versio

    Fingolimod modulates microglial activation to augment markers of remyelination

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

    Predictions for the Spatial Distribution of Gluons in the Initial Nuclear State

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    We make predictions for the t-differential cross section of exclusive vector meson production (EVMP) in electron-ion collisions, with the aim of comparing DGLAP evolution to CGC models. In the current picture for the high-energy nucleus, nonlinear effects need to be understood in terms of low-xx gluon radiation and recombination as well as how this leads to saturation. EVMP grants experimental access to the edge region of the highly-boosted nuclear wavefunction, where the saturation scale for CGC calculations becomes inaccessible to pQCD. On the other hand, DGLAP evolution requires careful consideration of unitarity effects. The existing J/ψJ/{\psi} photoproduction data in ep collisions provides a baseline for these theoretical calculations. Under different small-xx frameworks we obtain a measurable distinction in both the shape and normalization of the differential cross section predictions. These considerations are relevant for heavy ion collisions because the initial state may be further constrained, thus aiding in quantitative study of the quark-gluon plasma.Comment: 4 pages, 2 figures, 6th Hard Probes Conference 201
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