The Euclidean $ϕ^4_2$ theory as a limit of an inhomogeneous Bose gas

Fuente: arXiv
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Hauptverfasser: Caraci, Cristina, Knowles, Antti, Ranallo, Alessio, Giesteira, Pedro Torres
Format: Preprint
Veröffentlicht: 2026
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author Caraci, Cristina
Knowles, Antti
Ranallo, Alessio
Giesteira, Pedro Torres
author_facet Caraci, Cristina
Knowles, Antti
Ranallo, Alessio
Giesteira, Pedro Torres
contents We prove that the grand canonical Gibbs state of an interacting two-dimensional quantum Bose gas confined by a trapping potential converges to the complex Euclidean field theory with local quartic self-interaction, when the density of the gas becomes large and the range of the interaction becomes small. We obtain convergence of the relative partition function and convergence in $L^1 \cap L^\infty$ of the renormalised reduced density matrices. The field theory is supported on distributions of negative regularity, which requires a renormalisation by divergent mass and energy counterterms. Unlike previous results in the homogeneous setting of the torus without a trapping potential, the counterterms are not given by a finite collection of scalars but by diverging counterterm functions. This leads to significant new mathematical challenges. For our proof, we also derive quantitative bounds on the Green function of Schrödinger operators and of its gradient, which might be of independent interest.
format Preprint
id arxiv_https___arxiv_org_abs_2603_12241
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Euclidean $ϕ^4_2$ theory as a limit of an inhomogeneous Bose gas
Caraci, Cristina
Knowles, Antti
Ranallo, Alessio
Giesteira, Pedro Torres
Mathematical Physics
Analysis of PDEs
Probability
35Q55, 81V70, 60G60, 82B10, 35Q40, 81T08
We prove that the grand canonical Gibbs state of an interacting two-dimensional quantum Bose gas confined by a trapping potential converges to the complex Euclidean field theory with local quartic self-interaction, when the density of the gas becomes large and the range of the interaction becomes small. We obtain convergence of the relative partition function and convergence in $L^1 \cap L^\infty$ of the renormalised reduced density matrices. The field theory is supported on distributions of negative regularity, which requires a renormalisation by divergent mass and energy counterterms. Unlike previous results in the homogeneous setting of the torus without a trapping potential, the counterterms are not given by a finite collection of scalars but by diverging counterterm functions. This leads to significant new mathematical challenges. For our proof, we also derive quantitative bounds on the Green function of Schrödinger operators and of its gradient, which might be of independent interest.
title The Euclidean $ϕ^4_2$ theory as a limit of an inhomogeneous Bose gas
topic Mathematical Physics
Analysis of PDEs
Probability
35Q55, 81V70, 60G60, 82B10, 35Q40, 81T08
url https://arxiv.org/abs/2603.12241