18,659 research outputs found

    Novel black hole bound states and entropy

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    We solve for the spectrum of the Laplacian as a Hamiltonian on R2D\mathbb{R}^{2}-\mathbb{D} and in R3B\mathbb{R}^{3}-\mathbb{B}. A self-adjointness analysis with D\partial\mathbb{D} and B\partial\mathbb{B} as the boundary for the two cases shows that a general class of boundary conditions for which the Hamiltonian operator is essentially self-adjoint are of the mixed (Robin) type. With this class of boundary conditions we obtain "bound state" solutions for the Schroedinger equation. Interestingly, these solutions are all localized near the boundary. We further show that the number of bound states is finite and is in fact proportional to the perimeter or area of the removed \emph{disc} or \emph{ball}. We then argue that similar considerations should hold for static black hole backgrounds with the horizon treated as the boundary.Comment: 13 pages, 3 figures, approximate formula for energy spectrum added at the end of section 2.1 along with additional minor changes to comply with the version accepted in PR

    Some Hamiltonian Models of Friction

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    Mathematical results on some models describing the motion of a tracer particle through a Bose-Einstein condensate are described. In the limit of a very dense, very weakly interacting Bose gas and for a very large particle mass, the dynamics of the coupled system is determined by classical non-linear Hamiltonian equations of motion. The particle's motion exhibits deceleration corresponding to friction (with memory) caused by the emission of Cerenkov radiation of gapless modes into the gas. Precise results are stated and outlines of proofs are presented. Some technical details are deferred to forthcoming papers.Comment: 19 Pages, 1 figur

    Parasitism, Adult Emergence, Sex Ratio, and Size of \u3ci\u3eAphidius Colemani\u3c/i\u3e (Hymenoptera: Aphidiidae) on Several Aphid Species

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    Aphidius colemani Viereck parasitizes several economically important aphid pests of small grain crops including the greenbug, Schizaphis graminum and the Russian wheat aphid, Diuraphis noxia. The ability of A. colemani to switch from S. graminum to several species of aphids common to agricultural and associated non-agricultural ecosystems in the Great Plains, and the effects of host-change on several biological parameters that influence population growth rate were determined. Female A. colemani parasitized and developed to adulthood in nine of 14 aphid species to which they were exposed in the laboratory. All small grain feeding aphids except Sipha flava were parasi­tized. Two sunflower feeding species (Aphis nerii and A. helianthi) and two crucifer feeding species (Lipaphis erysimi and Brevicoryne brassicae) were parasitized, as was the cotton aphid. Aphis gossypii. The average percentage of aphids parasitized differed significantly among host aphid species. as did the percentage of parasitoids surviving from the mummy to the adult stage and the time required for immature development. The sex ratio of adults that enclosed from the various hosts did not differ significantly among species. Dry weights of adult parasitoids differed significantly among host species. Adults from S. graminum weighed most (0.054 mg) while those emerging from A. helianthi weighed least (0.020 mg). Results are discussed in terms of strategies for classical biological control of aphid pests of cereals

    On the Flux-Across-Surfaces Theorem

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    The quantum probability flux of a particle integrated over time and a distant surface gives the probability for the particle crossing that surface at some time. We prove the free Flux-Across-Surfaces Theorem, which was conjectured by Combes, Newton and Shtokhamer, and which relates the integrated quantum flux to the usual quantum mechanical formula for the cross section. The integrated quantum flux is equal to the probability of outward crossings of surfaces by Bohmian trajectories in the scattering regime.Comment: 13 pages, latex, 1 figure, very minor revisions, to appear in Letters in Mathematical Physics, Vol. 38, Nr.

    Diamagnetism of quantum gases with singular potentials

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    We consider a gas of quasi-free quantum particles confined to a finite box, subjected to singular magnetic and electric fields. We prove in great generality that the finite volume grand-canonical pressure is jointly analytic in the chemical potential ant the intensity of the external magnetic field. We also discuss the thermodynamic limit

    Analysis of unbounded operators and random motion

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    We study infinite weighted graphs with view to \textquotedblleft limits at infinity,\textquotedblright or boundaries at infinity. Examples of such weighted graphs arise in infinite (in practice, that means \textquotedblleft very\textquotedblright large) networks of resistors, or in statistical mechanics models for classical or quantum systems. But more generally our analysis includes reproducing kernel Hilbert spaces and associated operators on them. If XX is some infinite set of vertices or nodes, in applications the essential ingredient going into the definition is a reproducing kernel Hilbert space; it measures the differences of functions on XX evaluated on pairs of points in XX. And the Hilbert norm-squared in H(X)\mathcal{H}(X) will represent a suitable measure of energy. Associated unbounded operators will define a notion or dissipation, it can be a graph Laplacian, or a more abstract unbounded Hermitian operator defined from the reproducing kernel Hilbert space under study. We prove that there are two closed subspaces in reproducing kernel Hilbert space H(X)\mathcal{H}(X) which measure quantitative notions of limits at infinity in XX, one generalizes finite-energy harmonic functions in H(X)\mathcal{H}(X), and the other a deficiency index of a natural operator in H(X)\mathcal{H}(X) associated directly with the diffusion. We establish these results in the abstract, and we offer examples and applications. Our results are related to, but different from, potential theoretic notions of \textquotedblleft boundaries\textquotedblright in more standard random walk models. Comparisons are made.Comment: 38 pages, 4 tables, 3 figure

    Finite lifetime eigenfunctions of coupled systems of harmonic oscillators

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    We find a Hermite-type basis for which the eigenvalue problem associated to the operator HA,B:=B(x2)+Ax2H_{A,B}:=B(-\partial_x^2)+Ax^2 acting on L2(R;C2)L^2({\bf R};{\bf C}^2) becomes a three-terms recurrence. Here AA and BB are two constant positive definite matrices with no other restriction. Our main result provides an explicit characterization of the eigenvectors of HA,BH_{A,B} that lie in the span of the first four elements of this basis when ABBAAB\not= BA.Comment: 11 pages, 1 figure. Some typos where corrected in this new versio

    Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

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    Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and hydrostatic equilibrium, with constraints from conservation of energy and pressure balance at the cluster boundary. The resulting properties of the gas for these simulated redshift zero clusters (the temperature distribution, mass-temperature and luminosity-temperature relations, and the gas fraction) are compared with observations in the X-ray of nearby clusters. The observed properties are reproduced only under the assumption that substantial energy injection from non-gravitational sources has occurred. Our model does not specify the source, but star formation and AGN may be capable of providing this energy, which amounts to 3 to 5 x10^{-5} of the rest mass in stars (assuming ten percent of the gas initially in the cluster forms stars). With the method described here it is possible to generate realistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-body simulations, with the distributions of internal halo properties (and their trends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure

    Asymptotics for the number of eigenvalues of three-particle Schr\"{o}dinger operators on lattices

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    We consider the Hamiltonian of a system of three quantum mechanical particles (two identical fermions and boson)on the three-dimensional lattice Z3\Z^3 and interacting by means of zero-range attractive potentials. We describe the location and structure of the essential spectrum of the three-particle discrete Schr\"{o}dinger operator Hγ(K),H_{\gamma}(K), KK being the total quasi-momentum and γ>0\gamma>0 the ratio of the mass of fermion and boson. We choose for γ>0\gamma>0 the interaction v(γ)v(\gamma) in such a way the system consisting of one fermion and one boson has a zero energy resonance. We prove for any γ>0\gamma> 0 the existence infinitely many eigenvalues of the operator Hγ(0).H_{\gamma}(0). We establish for the number N(0,γ;z;)N(0,\gamma; z;) of eigenvalues lying below z<0z<0 the following asymptotics limz0N(0,γ;z)logz=U(γ). \lim_{z\to 0-}\frac{N(0,\gamma;z)}{\mid \log \mid z\mid \mid}={U} (\gamma) . Moreover, for all nonzero values of the quasi-momentum KT3K \in T^3 we establish the finiteness of the number N(K,γ;τess(K)) N(K,\gamma;\tau_{ess}(K)) of eigenvalues of H(K)H(K) below the bottom of the essential spectrum and we give an asymptotics for the number N(K,γ;0)N(K,\gamma;0) of eigenvalues below zero.Comment: 25 page

    Dipoles in Graphene Have Infinitely Many Bound States

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    We show that in graphene charge distributions with non-vanishing dipole moment have infinitely many bound states. The corresponding eigenvalues accumulate at the edges of the gap faster than any power
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