Factorization of solutions of linear differential equations

Fuente: arXiv
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Autore principale: Gröhn, Janne
Natura: Preprint
Pubblicazione: 2025
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author Gröhn, Janne
author_facet Gröhn, Janne
contents This paper supplements recents results on linear differential equations $f''+Af=0$, where the coefficient $A$ is analytic in the unit disc of the complex plane $\mathbb{C}$. It is shown that, if $A$ is analytic and $|A(z)|^2(1-|z|^2)^3\, dm(z)$ is a Carleson measure, then all non-trivial solutions of $f''+Af=0$ can be factorized as $f=Be^g$, where $B$ is a Blaschke product whose zero-sequence $Λ$ is uniformly separated and where $g\in{\rm BMOA}$ satisfies the interpolation property $$g'(z_n) = -\frac{1}{2} \, \frac{B''(z_n)}{B'(z_n)}, \quad z_n\inΛ.$$ Among other things, this factorization implies that all solutions of $f''+Af=0$ are functions in a Hardy space and have no singular inner factors. Zero-free solutions play an important role as their maximal growth is similar to the general case. The study of zero-free solutions produces a new result on Riccati differential equations.
format Preprint
id arxiv_https___arxiv_org_abs_2501_09508
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Factorization of solutions of linear differential equations
Gröhn, Janne
Classical Analysis and ODEs
Complex Variables
Primary 34M10, Secondary 30H30, 30H35
This paper supplements recents results on linear differential equations $f''+Af=0$, where the coefficient $A$ is analytic in the unit disc of the complex plane $\mathbb{C}$. It is shown that, if $A$ is analytic and $|A(z)|^2(1-|z|^2)^3\, dm(z)$ is a Carleson measure, then all non-trivial solutions of $f''+Af=0$ can be factorized as $f=Be^g$, where $B$ is a Blaschke product whose zero-sequence $Λ$ is uniformly separated and where $g\in{\rm BMOA}$ satisfies the interpolation property $$g'(z_n) = -\frac{1}{2} \, \frac{B''(z_n)}{B'(z_n)}, \quad z_n\inΛ.$$ Among other things, this factorization implies that all solutions of $f''+Af=0$ are functions in a Hardy space and have no singular inner factors. Zero-free solutions play an important role as their maximal growth is similar to the general case. The study of zero-free solutions produces a new result on Riccati differential equations.
title Factorization of solutions of linear differential equations
topic Classical Analysis and ODEs
Complex Variables
Primary 34M10, Secondary 30H30, 30H35
url https://arxiv.org/abs/2501.09508