Complex exceptional orthogonal polynomials and quasi-invariance

Abstract

Consider the Wronskians of the classical Hermite polynomials $$H_{\lambda ,l}(x):=\mathrm{Wr}(H_l(x),H_{k_1}(x),\dots ,H_{k_n}(x)),l\in {\mathbb{Z}}_{\ge 0},$$ where $k_i={\lambda }_i+n-i,i=1,\dots ,n$ and $\lambda =({\lambda }_1,\dots ,{\lambda }_n)$ is a partition. Gómez-Ullate et al showed that for a special class of partitions the corresponding polynomials are orthogonal and dense among all polynomials with certain inner product, but in contrast to the usual case have some degrees missing (so called exceptional orthogonal polynomials). We generalise their results to all partitions by considering complex contours of integration and non-positive Hermitian products. The corresponding polynomials are orthogonal and dense in a finite-codimensional subspace of $\mathbb{C}[x]$ satisfying certain quasi-invariance conditions. A Laurent version of exceptional orthogonal polynomials, related to monodromy-free trigonometric Schrödinger operators, is also presented.

18 pages

References in corpus (2)

• Oscillation theorems for the Wronskian of an arbitrary sequence of eigenfunctions of Schrödinger's equation
• On the rational monodromy-free potentials with sextic growth

Cited by in corpus (5)

• Shape invariance and equivalence relations for pseudowronskians of Laguerre and Jacobi polynomials
• Coefficients of Wronskian Hermite polynomials
• Recurrence Relations for Wronskian Hermite Polynomials
• Quasi-invariant Hermite polynomials and Lassalle-Nekrasov correspondence
• Exceptional Hermite Polynomials and Calogero-Moser Pairs