Abstract
We consider a class of Jacobi matrices with unbounded entries in the so-called critical (double root, Jordan block) case. We prove a formula which relates the spectral density of a matrix to the asymptotics of orthogonal polynomials associated with it.
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Notes
The branch of the square root should be chosen so that its values are positive for positive \(\lambda\).
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Funding
The first author was supported by the RFBR grant 19-01-00657A, by the Knut and Alice Wallenberg Foundation (Sections 1–3), and by the RScF grant 20-11-20032 (Section 4). He appreciates the hospitality of the Mittag-Leffler Institute, where a part of this work was done. The second author was supported by the RFBR grant 19-01-00565A (Sections 1–3) and by the RScF grant 20-11-20032 (Section 4).
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Translated from Funktsional'nyi Analiz i ego Prilozheniya, 2021, Vol. 55, pp. 21–43 https://doi.org/10.4213/faa3857.
To the memory of M. Z. Solomyak
Translated by S. A. Simonov
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Naboko, S.N., Simonov, S.A. Titchmarsh–Weyl Formula for the Spectral Density of a Class of Jacobi Matrices in the Critical Case. Funct Anal Its Appl 55, 94–112 (2021). https://doi.org/10.1134/S0016266321020027
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DOI: https://doi.org/10.1134/S0016266321020027