Plancherel–Rotach edge asymptotic conjecture for orthonormal polynomials

Let {P^k(x)}k=1n\{\widehat P_k(x)\}_{k=1}^n be a sequence of polynomials orthonormal with respect to a weight function w(x)w(x) on an unbounded interval, and let tnt_n be the large transition point of P^n(x)\widehat P_n(x). Assume the interval is (0,)(0,\infty) or (,)(-\infty,\infty). Suppose that

logw(x)=O(xm)as x.-\log w(x)=O(x^m)\qquad\text{as }x\to\infty.

Then the Plancherel–Rotach edge asymptotic conjecture asserts that

tn=O(n1/m)as n.t_n=O\left(n^{1/m}\right)\qquad\text{as }n\to\infty.

Moreover, uniformly for bounded real ss, with x=tn(1+sn2/3)x=t_n(1+sn^{-2/3}),

w(x)1/2P^n(x)c^(s)nk(1+o(1))as n,w(x)^{1/2}\widehat P_n(x)\sim \hat c(s)n^k(1+o(1))\qquad\text{as }n\to\infty,

where c^(s)\hat c(s) is uniformly bounded in ss and

k=1612m.k=\frac16-\frac{1}{2m}.

The conjecture predicts the transition-point scale and the edge amplitude for a broad class of orthonormal polynomials with weights having polynomial logarithmic decay; the source provides the formulation but no resolution, so its status is open.

Sources & referencesView supporting material

Primary source

Dan Dai, Mourad E. H. Ismail and Xiang-Sheng Wang, “Plancherel-Rotach asymptotic expansion for some polynomials from indeterminate moment problems”, arXiv:1302.6196 (2013).

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