98 research outputs found

    Asymptotics for the Fredholm Determinant of the Sine Kernel on a Union of Intervals

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    In the bulk scaling limit of the Gaussian Unitary Ensemble of Hermitian matrices the probability that an interval of length ss contains no eigenvalues is the Fredholm determinant of the sine kernel sin(xy)π(xy)\sin(x-y)\over\pi(x-y) over this interval. A formal asymptotic expansion for the determinant as ss tends to infinity was obtained by Dyson. In this paper we replace a single interval of length ss by sJsJ where JJ is a union of mm intervals and present a proof of the asymptotics up to second order. The logarithmic derivative with respect to ss of the determinant equals a constant (expressible in terms of hyperelliptic integrals) times ss, plus a bounded oscillatory function of ss (zero of m=1m=1, periodic if m=2m=2, and in general expressible in terms of the solution of a Jacobi inversion problem), plus o(1)o(1). Also determined are the asymptotics of the trace of the resolvent operator, which is the ratio in the same model of the probability that the set contains exactly one eigenvalue to the probability that it contains none. The proofs use ideas from orthogonal polynomial theory.Comment: 24 page

    Organic Superconductors: when correlations and magnetism walk in

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    This survey provides a brief account for the start of organic superconductivity motivated by the quest for high Tc superconductors and its development since the eighties'. Besides superconductivity found in 1D organics in 1980, progresses in this field of research have contributed to better understand the physics of low dimensional conductors highlighted by the wealth of new remarkable properties. Correlations conspire to govern the low temperature properties of the metallic phase. The contribution of antiferromagnetic fluctuations to the interchain Cooper pairing proposed by the theory is borne out by experimental investigations and supports supercondutivity emerging from a non Fermi liquid background. Quasi one dimensional organic superconductors can therefore be considered as simple prototype systems for the more complex high Tc materials.Comment: 41 pages, 21 figures to be published in Journal of Superconductivity and Novel Magnetis

    Effects on profits and risks of hedging hogs in the futures market

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    Swine Day '76 is known as Swine Day, 1976Erratic hog prices in recent years have compounded management problems. As a result, interest has increased in ways of tying down prices before the hogs are ready for market. This report presents results of a study of one approach to the problem -- hedging in the futures market
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