Vacuum and thermal fluctuations of a scalar field with point interactions

Fuente: arXiv
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Autori principali: Fermi, Davide, Gurgoglione, Marco
Natura: Preprint
Pubblicazione: 2026
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author Fermi, Davide
Gurgoglione, Marco
author_facet Fermi, Davide
Gurgoglione, Marco
contents We investigate the vacuum and thermal fluctuations of a neutral massless scalar field living in Minkowski spacetime and interacting with a finite number of point-like obstacles, modelled by zero-range potentials. The system is described rigorously in terms of self-adjoint realizations of the Laplacian, under assumptions ensuring the absence of instabilities. Using the relative zeta-function technique, we determine the renormalized connected partition function and derive explicit expressions for the thermodynamic observables, characterizing both their low- and high-temperature behaviours. Furthermore, we derive of a convergent Born series expansion for the Casimir energy, which identifies multiple-scattering processes as the mechanism underlying vacuum forces. The latter decompose into pairwise contributions directed along the lines joining the obstacles, with intensities depending non-locally on the full configuration. We also present some numerical results for identical obstacles, indicating that the Casimir forces are always attractive in this context.
format Preprint
id arxiv_https___arxiv_org_abs_2605_10725
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Vacuum and thermal fluctuations of a scalar field with point interactions
Fermi, Davide
Gurgoglione, Marco
Mathematical Physics
Mesoscale and Nanoscale Physics
Quantum Physics
81T55, 81T20, 81T28, 81U15, 81Q10
We investigate the vacuum and thermal fluctuations of a neutral massless scalar field living in Minkowski spacetime and interacting with a finite number of point-like obstacles, modelled by zero-range potentials. The system is described rigorously in terms of self-adjoint realizations of the Laplacian, under assumptions ensuring the absence of instabilities. Using the relative zeta-function technique, we determine the renormalized connected partition function and derive explicit expressions for the thermodynamic observables, characterizing both their low- and high-temperature behaviours. Furthermore, we derive of a convergent Born series expansion for the Casimir energy, which identifies multiple-scattering processes as the mechanism underlying vacuum forces. The latter decompose into pairwise contributions directed along the lines joining the obstacles, with intensities depending non-locally on the full configuration. We also present some numerical results for identical obstacles, indicating that the Casimir forces are always attractive in this context.
title Vacuum and thermal fluctuations of a scalar field with point interactions
topic Mathematical Physics
Mesoscale and Nanoscale Physics
Quantum Physics
81T55, 81T20, 81T28, 81U15, 81Q10
url https://arxiv.org/abs/2605.10725