On two-dimensional Dirac operators with critical delta-shell interactions

Fuente: arXiv
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Main Authors: Borrelli, William, Carimati, Pietro, Fermi, Davide
Format: Preprint
Published: 2026
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author Borrelli, William
Carimati, Pietro
Fermi, Davide
author_facet Borrelli, William
Carimati, Pietro
Fermi, Davide
contents We study two-dimensional Dirac operators with singular interactions of electrostatic and Lorentzscalar type, supported either on a straight line or a circle. For certain critical values of the interaction strengths, the essential spectrum of such operators comprises an isolated point lying within the mass gap. We clarify the nature of this point in both geometries. For the straight line model, this point is known to be an eigenvalue of infinite multiplicity, and we provide a detailed analysis of the corresponding eigenfunctions. By contrast, in the case of a circle, we show that the said point is not itself an eigenvalue, but rather an accumulation point of a double sequence of simple eigenvalues. In view of the high degree of symmetry of the configurations under analysis, this behavior is unexpected and our findings lead us to formulate some conjectures concerning critical singular interactions supported on generic smooth curves.
format Preprint
id arxiv_https___arxiv_org_abs_2601_23053
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On two-dimensional Dirac operators with critical delta-shell interactions
Borrelli, William
Carimati, Pietro
Fermi, Davide
Spectral Theory
Mathematical Physics
Analysis of PDEs
We study two-dimensional Dirac operators with singular interactions of electrostatic and Lorentzscalar type, supported either on a straight line or a circle. For certain critical values of the interaction strengths, the essential spectrum of such operators comprises an isolated point lying within the mass gap. We clarify the nature of this point in both geometries. For the straight line model, this point is known to be an eigenvalue of infinite multiplicity, and we provide a detailed analysis of the corresponding eigenfunctions. By contrast, in the case of a circle, we show that the said point is not itself an eigenvalue, but rather an accumulation point of a double sequence of simple eigenvalues. In view of the high degree of symmetry of the configurations under analysis, this behavior is unexpected and our findings lead us to formulate some conjectures concerning critical singular interactions supported on generic smooth curves.
title On two-dimensional Dirac operators with critical delta-shell interactions
topic Spectral Theory
Mathematical Physics
Analysis of PDEs
url https://arxiv.org/abs/2601.23053