The Singular Values of the GOE

TL;DR

This paper uncovers a structured relationship between the singular values of the GOE and other ensembles, providing new insights into their distribution, determinant behavior, and gap probabilities, with simplified analysis avoiding complex mathematical tools.

Contribution

It introduces a novel structure of GOE singular values linking them to chiral ensembles and independent chi-distributed variables, simplifying analysis of their properties.

Findings

Even-location singular values follow the distribution of positive eigenvalues of anti-GUE.

The determinant magnitude of GOE matrices is a product of independent random variables.

GOE gap probabilities can be expressed via the Laguerre unitary ensemble.

Abstract

As a unifying framework for examining several properties that nominally involve eigenvalues, we present a particular structure of the singular values of the Gaussian orthogonal ensemble (GOE): the even-location singular values are distributed as the positive eigenvalues of a Gaussian ensemble with chiral unitary symmetry (anti-GUE), while the odd-location singular values, conditioned on the even-location ones, can be algebraically transformed into a set of independent $\chi$-distributed random variables. We discuss three applications of this structure: first, there is a pair of bidiagonal square matrices, whose singular values are jointly distributed as the even- and odd-location ones of the GOE; second, the magnitude of the determinant of the GOE is distributed as a product of simple independent random variables; third, on symmetric intervals, the gap probabilities of the GOE can be expressed in terms of the Laguerre unitary ensemble (LUE). We work specifically with matrices of finite order, but by passing to a large matrix limit, we also obtain new insight into asymptotic properties such as the central limit theorem of the determinant or the gap probabilities in the bulk-scaling limit. The analysis in this paper avoids much of the technical machinery (e.g. Pfaffians, skew-orthogonal polynomials, martingales, Meijer $G$-function, etc.) that was previously used to analyze some of the applications.