7,649 research outputs found

    On the leading coefficient of polynomials orthogonal over domains with corners

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    Let GG be the interior domain of a piecewise analytic Jordan curve without cusps. Let {pn}n=0\{p_n\}_{n=0}^\infty be the sequence of polynomials that are orthonormal over GG with respect to the area measure, with each pnp_n having leading coefficient λn>0\lambda_n>0. N. Stylianopoulos has recently proven that the asymptotic behavior of λn\lambda_n as nn\to\infty is given by n+1πγ2n+2λn2=1αn, \frac{n+1}{\pi}\frac{\gamma^{2n+2}}{ \lambda_n^{2}}=1-\alpha_n, where αn=O(1/n)\alpha_n=O(1/n) as nn\to\infty and γ\gamma is the reciprocal of the logarithmic capacity of the boundary G\partial G. In this paper, we prove that the O(1/n)O(1/n) estimate for the error term αn\alpha_n is, in general, best possible, by exhibiting an example for which lim infnnαn>0. \liminf_{n\to\infty}\,n\alpha_n>0. The proof makes use of the Faber polynomials, about which a conjecture is formulated.Comment: 7 page

    The Coexistence of Classical Bulges, Pseudobulges, and Supermassive Black Holes

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    Some S0 and early-type spiral galaxies possess "composite bulges"; in these galaxies, the photometric bulge -- the central stellar light in excess of the disk light -- is composed of both a "(disky) pseudobulge", with a flattened, disklike morphology and relatively cool stellar kinematics, and a rounder, kinematically hot "classical bulge" embedded within. I speculate that supermassive black holes (SMBH) in such galaxies may correlate with the classical-bulge component only, and not with the pseudobulge component; preliminary comparisons with SMBH masses appear to support this hypothesis.Comment: LaTeX, 4 pages, 2 PDF figures. To appear in the proceedings of "The Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters", eds. Sebastian Heinz and Eric Wilcots (AIP conference series

    Can D-Branes Wrap Nonrepresentable Cycles?

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    Sometimes a homology cycle of a nonsingular compactification manifold cannot be represented by a nonsingular submanifold. We want to know whether such nonrepresentable cycles can be wrapped by D-branes. A brane wrapping a representable cycle carries a K-theory charge if and only if its Freed-Witten anomaly vanishes. However some K-theory charges are only carried by branes that wrap nonrepresentable cycles. We provide two examples of Freed-Witten anomaly-free D6-branes wrapping nonrepresentable cycles in the presence of a trivial NS 3-form flux. The first occurs in type IIA string theory compactified on the Sp(2) group manifold and the second in IIA on a product of lens spaces. We find that the first D6-brane carries a K-theory charge while the second does not.Comment: 11 pages, no figure
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