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The density of states of a local almost periodic operator in ν

Andrzej Krupa (2003)

Studia Mathematica

We prove the existence of the density of states of a local, self-adjoint operator determined by a coercive, almost periodic quadratic form on H m ( ν ) . The support of the density coincides with the spectrum of the operator in L ² ( ν ) .

The Leray measure of nodal sets for random eigenfunctions on the torus

Ferenc Oravecz, Zeév Rudnick, Igor Wigman (2008)

Annales de l’institut Fourier

We study nodal sets for typical eigenfunctions of the Laplacian on the standard torus in d 2 dimensions. Making use of the multiplicities in the spectrum of the Laplacian, we put a Gaussian measure on the eigenspaces and use it to average over the eigenspace. We consider a sequence of eigenvalues with growing multiplicity 𝒩 .The quantity that we study is the Leray, or microcanonical, measure of the nodal set. We show that the expected value of the Leray measure of an eigenfunction is constant, equal...

The Weyl asymptotic formula by the method of Tulovskiĭ and Shubin

Paweł Głowacki (1998)

Studia Mathematica

Let A be a pseudodifferential operator on N whose Weyl symbol a is a strictly positive smooth function on W = N × N such that | α a | C α a 1 - ϱ for some ϱ>0 and all |α|>0, α a is bounded for large |α|, and l i m w a ( w ) = . Such an operator A is essentially selfadjoint, bounded from below, and its spectrum is discrete. The remainder term in the Weyl asymptotic formula for the distribution of the eigenvalues of A is estimated. This is done by applying the method of approximate spectral projectors of Tulovskiĭ and Shubin.

Tunnel effect and symmetries for non-selfadjoint operators

Michael Hitrik (2013)

Journées Équations aux dérivées partielles

We study low lying eigenvalues for non-selfadjoint semiclassical differential operators, where symmetries play an important role. In the case of the Kramers-Fokker-Planck operator, we show how the presence of certain supersymmetric and 𝒫𝒯 -symmetric structures leads to precise results concerning the reality and the size of the exponentially small eigenvalues in the semiclassical (here the low temperature) limit. This analysis also applies sometimes to chains of oscillators coupled to two heat baths,...

Two remarks about spectral asymptotics of pseudodifferential operators

Wojciech Czaja, Ziemowit Rzeszotnik (1999)

Colloquium Mathematicae

In this paper we show an asymptotic formula for the number of eigenvalues of a pseudodifferential operator. As a corollary we obtain a generalization of the result by Shubin and Tulovskiĭ about the Weyl asymptotic formula. We also consider a version of the Weyl formula for the quasi-classical asymptotics.

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