21,570 research outputs found

    Towards a quantum field theory of primitive string fields

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    We denote generating functions of massless even higher spin fields "primitive string fields" (PSF's). In an introduction we present the necessary definitions and derive propagators and currents of these PDF's on flat space. Their off-shell cubic interaction can be derived after all off-shell cubic interactions of triplets of higher spin fields have become known [2],[3]. Then we discuss four-point functions of any quartet of PSF's. In subsequent sections we exploit the fact that higher spin field theories in AdSd+1AdS_{d+1} are determined by AdS/CFT correspondence from universality classes of critical systems in dd dimensional flat spaces. The O(N) invariant sectors of the O(N) vector models for 1≤N≤∞1\leq N \leq \infty play for us the role of "standard models", for varying NN, they contain e.g. the Ising model for N=1 and the spherical model for N=∞N=\infty. A formula for the masses squared that break gauge symmetry for these O(N) classes is presented for d = 3. For the PSF on AdSAdS space it is shown that it can be derived by lifting the PSF on flat space by a simple kernel which contains the sum over all spins. Finally we use an algorithm to derive all symmetric tensor higher spin fields. They arise from monomials of scalar fields by derivation and selection of conformal (quasiprimary) fields. Typically one monomial produces a multiplet of spin ss conformal higher spin fields for all s≥4s \geq 4, they are distinguished by their anomalous dimensions (in CFT3CFT_3) or by their mass (in AdS4AdS_4). We sum over these multiplets and the spins to obtain "string type fields", one for each such monomial.Comment: 16 pages,Late

    The critical O(NN) σ\sigma-model at dimension 2<d<42<d<4: Hardy-Ramanujan distribution of quasi-primary fields and a collective fusion approach

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    The distribution of quasiprimary fields of fixed classes characterized by their O(N)(N) representations YY and the number pp of vector fields from which they are composed at N=∞N=\infty in dependence on their normal dimension [δ][\delta] is shown to obey a Hardy-Ramanujan law at leading order in a 1N\frac{1}{N}-expansion. We develop a method of collective fusion of the fundamental fields which yields arbitrary \qps and resolves any degeneracy.Comment: KL-TH-94/2, 21 pages (uuencoded Postscript file

    The Rocketdyne Multifunction Tester. Part 2: Operation of a Radial Magnetic Bearing as an Excitation Source

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    The operation of the magnetic bearing used as an excitation source in the Rocketdyne Multifunction Tester is described. The tester is scheduled for operation during the summer of 1990. The magnetic bearing can be used in two control modes: (1) open loop mode, in which the magnetic bearing operates as a force actuator; and (2) closed loop mode, in which the magnetic bearing provides shaft support. Either control mode can be used to excite the shaft; however, response of the shaft in the two control modes is different due to the alteration of the eigenvalues by closed loop mode operation. A rotordynamic model is developed to predict the frequency response of the tester due to excitation in either control mode. Closed loop mode excitation is shown to be similar to the excitation produced by a rotating eccentricity in a conventional bearing. Predicted frequency response of the tester in the two control modes is compared, and the maximum response is shown to be the same for the two control modes when synchronous unbalance loading is not considered. The analysis shows that the response of this tester is adequate for the extraction of rotordynamic stiffness, damping, and inertia coefficients over a wide range of test article stiffnesses

    Electron-Transport Properties of Na Nanowires under Applied Bias Voltages

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    We present first-principles calculations on electron transport through Na nanowires at finite bias voltages. The nanowire exhibits a nonlinear current-voltage characteristic and negative differential conductance. The latter is explained by the drastic suppression of the transmission peaks which is attributed to the electron transportability of the negatively biased plinth attached to the end of the nanowire. In addition, the finding that a voltage drop preferentially occurs on the negatively biased side of the nanowire is discussed in relation to the electronic structure and conduction.Comment: 4 pages, 6 figure

    Geometric Bogomolov conjecture for abelian varieties and some results for those with some degeneration (with an appendix by Walter Gubler: The minimal dimension of a canonical measure)

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    In this paper, we formulate the geometric Bogomolov conjecture for abelian varieties, and give some partial answers to it. In fact, we insist in a main theorem that under some degeneracy condition, a closed subvariety of an abelian variety does not have a dense subset of small points if it is a non-special subvariety. The key of the proof is the study of the minimal dimension of the components of a canonical measure on the tropicalization of the closed subvariety. Then we can apply the tropical version of equidistribution theory due to Gubler. This article includes an appendix by Walter Gubler. He shows that the minimal dimension of the components of a canonical measure is equal to the dimension of the abelian part of the subvariety. We can apply this result to make a further contribution to the geometric Bogomolov conjecture.Comment: 30 page

    The health of banking in the Third District

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    Banks and banking ; Bank failures
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