Fredholm determinants and pole-free solutions to the noncommutative Painleve' II equation

TL;DR

This paper extends integrable operator formalism to matrix-valued kernels, proving resolvent expressions via Riemann-Hilbert problems and constructing pole-free solutions to a noncommutative Painleve' II equation relevant for Fredholm determinant computations.

Contribution

It introduces a new formalism for matrix-valued convolution operators and constructs pole-free solutions to a noncommutative Painleve' II equation, linking integrable systems and noncommutative analysis.

Findings

Resolved matrix convolution operators using Riemann-Hilbert problems.

Constructed pole-free solutions for noncommutative Painleve' II.

Linked solutions to Fredholm determinants of matrix Airy kernels.

Abstract

We extend the formalism of integrable operators a' la Its-Izergin-Korepin-Slavnov to matrix-valued convolution operators on a semi-infinite interval and to matrix integral operators with a kernel of the form E_1^T(x) E_2(y)/(x+y) thus proving that their resolvent operators can be expressed in terms of solutions of some specific Riemann-Hilbert problems. We also describe some applications, mainly to a noncommutative version of Painleve' II (recently introduced by Retakh and Rubtsov), a related noncommutative equation of Painleve' type. We construct a particular family of solutions of the noncommutative Painleve' II that are pole-free (for real values of the variables) and hence analogous to the Hastings-McLeod solution of (commutative) Painleve' II. Such a solution plays the same role as its commutative counterpart relative to the Tracy-Widom theorem, but for the computation of the Fredholm determinant of a matrix version of the Airy kernel.