1,712 research outputs found

    Autocorrelations of the characteristic polynomial of a random matrix under microscopic scaling

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    We calculate the autocorrelation function for the characteristic polynomial of a random matrix in the microscopic scaling regime. While results fitting this description have be proved before, we will cover all values of inverse temperature β(0,)\beta \in (0,\infty). The method also differs from prior work, relying on matrix models introduced by Killip and Nenciu

    Matrix models for circular ensembles

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    We describe an ensemble of (sparse) random matrices whose eigenvalues follow the Gibbs distribution for n particles of the Coulomb gas on the unit circle at inverse temperature beta. Our approach combines elements from the theory of orthogonal polynomials on the unit circle with ideas from recent work of Dumitriu and Edelman. In particular, we resolve a question left open by them: find a tri-diagonal model for the Jacobi ensemble.Comment: 28 page

    Smooth solutions to the nonlinear wave equation can blow up on Cantor sets

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    We construct CC^\infty solutions to the one-dimensional nonlinear wave equation uttuxx2(p+2)p2upu=0withp>0 u_{tt} - u_{xx} - \tfrac{2(p+2)}{p^2} |u|^p u=0 \quad \text{with} \quad p>0 that blow up on any prescribed uniformly space-like CC^\infty hypersurface. As a corollary, we show that smooth solutions can blow up (at the first instant) on an arbitrary compact set. We also construct solutions that blow up on general space-like CkC^k hypersurfaces, but only when 4/p4/p is not an integer and k>(3p+4)/pk > (3p+4)/p

    Sum Rules for Jacobi Matrices and Their Applications to Spectral Theory

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    We discuss the proof of and systematic application of Case's sum rules for Jacobi matrices. Of special interest is a linear combination of two of his sum rules which has strictly positive terms. Among our results are a complete classification of the spectral measures of all Jacobi matrices J for which J-J_0 is Hilbert--Schmidt, and a proof of Nevai's conjecture that the Szego condition holds if J-J_0 is trace class.Comment: 69 pages, published versio
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