Quantitative spectral stability for Aharonov–Bohm operators with many coalescing poles
Veronica Felli
Università degli Studi di Milano-Bicocca, Milano, ItalyBenedetta Noris
Politecnico di Milano, Milano, ItalyRoberto Ognibene
Università di Pisa, Pisa, ItalyGiovanni Siclari
Politecnico di Milano, Milano, Italy

Abstract
The behaviour of simple eigenvalues of Aharonov–Bohm operators with many coalescing poles is discussed. In the case of half-integer circulation, a gauge transformation makes the problem equivalent to an eigenvalue problem for the Laplacian in a domain with straight cracks, lying along the moving directions of poles. For this problem, we obtain an asymptotic expansion for eigenvalues, in which the dominant term is related to the minimum of an energy functional associated with the configuration of poles and defined on a space of functions suitably jumping through the cracks.
Concerning configurations with an odd number of poles, an accurate blow-up analysis identifies the exact asymptotic behaviour of eigenvalues and the sign of the variation in some cases. An application to the special case of two poles is also discussed.
Cite this article
Veronica Felli, Benedetta Noris, Roberto Ognibene, Giovanni Siclari, Quantitative spectral stability for Aharonov–Bohm operators with many coalescing poles. J. Eur. Math. Soc. (2025), published online first
DOI 10.4171/JEMS/1632