Renormalized oscillation theory for singular linear Hamiltonian pencils

Fuente: arXiv
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Main Authors: Howard, Peter, Sukhtayev, Alim
Format: Preprint
Published: 2025
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author Howard, Peter
Sukhtayev, Alim
author_facet Howard, Peter
Sukhtayev, Alim
contents For many applications, critical information about system dynamics is encoded in associated eigenvalue problems that can be posed as linear Hamiltonian systems with suitable boundary conditions. Motivated by examples from hydrodynamics, quantum mechanics, and magnetohydrodynamics (MHD), we develop a general framework for analyzing a broad class of linear Hamiltonian systems with at least one singular boundary condition and possible nonlinear dependence on the spectral parameter. We show that renormalized oscillation results can be obtained in a natural way through consideration of the Maslov index associated with appropriately chosen paths of Lagrangian subspaces of $\mathbb{C}^{2n}$. This extends previous work by the authors for regular linear Hamiltonian systems that depend nonlinearly on the spectral parameter and singular linear Hamiltonian systems that depend linearly on the spectral parameter. We conclude the study by using our framework to study the spectrum in the setting of each of our motivating examples.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21016
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Renormalized oscillation theory for singular linear Hamiltonian pencils
Howard, Peter
Sukhtayev, Alim
Classical Analysis and ODEs
Dynamical Systems
34C10, 34C15, 35C07, 47A10
For many applications, critical information about system dynamics is encoded in associated eigenvalue problems that can be posed as linear Hamiltonian systems with suitable boundary conditions. Motivated by examples from hydrodynamics, quantum mechanics, and magnetohydrodynamics (MHD), we develop a general framework for analyzing a broad class of linear Hamiltonian systems with at least one singular boundary condition and possible nonlinear dependence on the spectral parameter. We show that renormalized oscillation results can be obtained in a natural way through consideration of the Maslov index associated with appropriately chosen paths of Lagrangian subspaces of $\mathbb{C}^{2n}$. This extends previous work by the authors for regular linear Hamiltonian systems that depend nonlinearly on the spectral parameter and singular linear Hamiltonian systems that depend linearly on the spectral parameter. We conclude the study by using our framework to study the spectrum in the setting of each of our motivating examples.
title Renormalized oscillation theory for singular linear Hamiltonian pencils
topic Classical Analysis and ODEs
Dynamical Systems
34C10, 34C15, 35C07, 47A10
url https://arxiv.org/abs/2510.21016