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arXiv · 2508.00803

Renormalization of generalized spin-boson models with critical ultraviolet divergences

Benjamin Alvarez·Sascha Lill·Davide Lonigro·Javier Valentín Martín
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Abstract

We provide a rigorous construction of generalized spin--boson models with commuting transition matrices and form factors exhibiting critical ultraviolet (UV) divergences. That is, we cover all divergences where a self-energy renormalization, but no non-Fock representation, is required. Our method is based on a direct definition of the renormalized Hamiltonian on a sufficiently large test domain, followed by a Friedrichs extension. We then prove that this Hamiltonian coincides with the one obtained by cut-off renormalization. Furthermore, we show that for specific supercritical cases, i.e., when a non-Fock representation is required, the renormalized Hamiltonian is trivial.

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Benjamin Alvarez, Sascha Lill, Davide Lonigro, Javier Valentín Martín. 2025-08-01. Renormalization of generalized spin-boson models with critical ultraviolet divergences. https://arxiv.org/abs/2508.00803

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