946 resultados para Spectral theory, differential operators, quantum graphs, indefinite operators
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2002 Mathematics Subject Classification: 35S05
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2002 Mathematics Subject Classification: 35L15, 35L80, 35S05, 35S30
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2000 Mathematics Subject Classification: 46B28, 47D15.
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MSC 2010: 54C35, 54C60.
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2000 Mathematics Subject Classification: Primary 47A48, 93B28, 47A65; Secondary 34C94.
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2000 Mathematics Subject Classification: 35S05.
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2000 Mathematics Subject Classification: 35L15, Secondary 35L30.
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We consider the Hamiltonian H of a 3D spinless non-relativistic quantum particle subject to parallel constant magnetic and non-constant electric field. The operator H has infinitely many eigenvalues of infinite multiplicity embedded in its continuous spectrum. We perturb H by appropriate scalar potentials V and investigate the transformation of these embedded eigenvalues into resonances. First, we assume that the electric potentials are dilation-analytic with respect to the variable along the magnetic field, and obtain an asymptotic expansion of the resonances as the coupling constant ϰ of the perturbation tends to zero. Further, under the assumption that the Fermi Golden Rule holds true, we deduce estimates for the time evolution of the resonance states with and without analyticity assumptions; in the second case we obtain these results as a corollary of suitable Mourre estimates and a recent article of Cattaneo, Graf and Hunziker [11]. Next, we describe sets of perturbations V for which the Fermi Golden Rule is valid at each embedded eigenvalue of H; these sets turn out to be dense in various suitable topologies. Finally, we assume that V decays fast enough at infinity and is of definite sign, introduce the Krein spectral shift function for the operator pair (H+V, H), and study its singularities at the energies which coincide with eigenvalues of infinite multiplicity of the unperturbed operator H.
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2000 Mathematics Subject Classification: 34E20, 35L80, 35L15.
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2000 Mathematics Subject Classification: Primary: 47B47, 47B10; secondary 47A30.
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2000 Mathematics Subject Classification: Primary 47A20, 47A45; Secondary 47A48.
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AMS classification: 41A36, 41A10, 41A25, 41Al7.
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2000 Mathematics Subject Classification: Primary: 34L25; secondary: 47A40, 81Q10.