1,425 research outputs found
Finite deficiency indices and uniform remainder in Weyl's law
We give a proof that in settings where Von Neumann deficiency indices are
finite the spectral counting functions of two different self-adjoint extensions
of the same symmetric operator differ by a uniformly bounded term (see also
Birman-Solomjak's 'Spectral Theory of Self-adjoint operators in Hilbert Space')
>. We apply this result to quantum graphs, pseudo-laplacians and surfaces with
conical singularities.Comment: 7 p., references adde
Eigenvalue variations and semiclassical concentration
We show that the behaviour of analytic eigenbranches of a Schr\"odinger
operator depends on the way eigenfunctions concentrate in the phase space.Comment: to be published in the proceedings of the conference 'Spectrum and
Dynamics', Montr\'eal, 200
Hyperbolic triangles without embedded eigenvalues
We consider the Neumann Laplacian acting on square-integrable functions on a
triangle in the hyperbolic plane that has one cusp. We show that the generic
such triangle has no eigenvalues embedded in its continuous spectrum. To prove
this result we study the behavior of the real-analytic eigenvalue branches of a
degenerating family of triangles. In particular, we use a careful analysis of
spectral projections near the crossings of these eigenvalue branches with the
eigenvalue branches of a model operator.Comment: 65 pages, 4 figures, to appear in Annals of Mathematics
http://annals.math.princeton.edu/articles/1159
Generic spectral simplicity of polygons
We study the Laplace operator with Dirichlet or Neumann boundary condition on
polygons in the Euclidean plane. We prove that almost every simply connected
polygon with at least four vertices has simple spectrum. We also address the
more general case of geodesic polygons in a constant curvature space form.Comment: length reduced to 6 pages, 1 figur
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