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Our goal is to find an asymptotic behavior as n→∞ of orthogonal polynomials P n(z) defined by the Jacobi recurrence coefficients a n,b n. We suppose that the off-diagonal coefficients a n grow so rapidly that the series ∑a n −1 converges, that is, the Carleman condition is violated. With respect to diagonal coefficients b n we assume that −b n(a na n−1) −1/2→2β ∞ for some β ∞≠±1. The asymptotic formulas obtained for P n(z) are quite different from the case ∑a n −1=∞ when the Carleman condition is satisfied. In particular, if ∑a n −1<∞, then the phase factors in these formulas do not depend on the spectral parameter z∈C. The asymptotic formulas obtained in the cases |β ∞|<1 and |β ∞|>1 are also qualitatively different from each other. As an application of these results, we find necessary and sufficient conditions for the essential self-adjointness of the corresponding minimal Jacobi operator.
Original language | English |
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Article number | 108648 |
Number of pages | 37 |
Journal | Journal of Functional Analysis |
Volume | 279 |
Issue number | 7 |
Early online date | 20 May 2020 |
DOIs | |
State | Published - 15 Oct 2020 |
ID: 71379271