Abstract
We obtain the strong asymptotics of polynomials p_n(lambda ), lambda in {mathbb {C}}, orthogonal with respect to measures in the complex plane of the form e-N(|λ|2s-tλs-t¯λ¯s)dA(λ),\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$\\begin{aligned} \\hbox {e}^{-N(|\\lambda |^{2s}-t\\lambda ^s-\\overline{t}\\overline{\\lambda }^s)}\\hbox {d}A(\\lambda ), \\end{aligned}$$\\end{document}where s is a positive integer, t is a complex parameter, and hbox {d}A stands for the area measure in the plane. This problem has its origin in normal matrix models. We study the asymptotic behavior of p_n(lambda ) in the limit n,Nrightarrow infty in such a way that n/Nrightarrow T constant. Such asymptotic behavior has two distinguished regimes according to the topology of the limiting support of the eigenvalues distribution of the normal matrix model. If 0<|t|^2<T/s, the eigenvalue distribution support is a simply connected compact set of the complex plane, while for |t|^2>T/s, the eigenvalue distribution support consists of s connected components. Correspondingly, the support of the limiting zero distribution of the orthogonal polynomials consists of a closed contour contained in each connected component. Our asymptotic analysis is obtained by reducing the planar orthogonality conditions of the polynomials to equivalent contour integral orthogonality conditions. The strong asymptotics for the orthogonal polynomials is obtained from the corresponding Riemann–Hilbert problem by the Deift–Zhou nonlinear steepest descent method.
Highlights
We study the asymptotics of orthogonal polynomials with respect to a family of measures supported on the whole complex plane
For the external potential W (λ) = |λ|2 +Re(tλ3), Bleher and Kuijlaars [11] defined polynomials orthogonal with respect to a system of unbounded contours on the complex plane, without any cut-off, and which satisfy the same recurrence relation that is asymptotically valid for the orthogonal polynomials of Elbau and Felder
In the work [6], the external potential W (λ) = |λ|2 − 2c log |λ − a| with c and a positive constants, has been studied, and the strong asymptotics of the corresponding orthogonal polynomials has been derived both in the case in which the support of the eigenvalues distribution is connected or multiply connected and critical transition was observed
Summary
We study the asymptotics of orthogonal polynomials with respect to a family of measures supported on the whole complex plane. For the external potential W (λ) = |λ|2 +Re(tλ3), Bleher and Kuijlaars [11] defined polynomials orthogonal with respect to a system of unbounded contours on the complex plane, without any cut-off, and which satisfy the same recurrence relation that is asymptotically valid for the orthogonal polynomials of Elbau and Felder They study the asymptotic distribution of the zeros of such polynomials confirming the predictions of [24]. In the work [6], the external potential W (λ) = |λ|2 − 2c log |λ − a| with c and a positive constants, has been studied, and the strong asymptotics of the corresponding orthogonal polynomials has been derived both in the case in which the support of the eigenvalues distribution is connected (pre-critical case) or multiply connected (post-critical case) and critical transition was observed (see [7,53]).
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