Thermodynamics from the S-matrix reloaded: emergent thermal mass

Fuente: arXiv
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Main Authors: Baratella, Pietro, Miro, Joan Elias
Format: Preprint
Published: 2025
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author Baratella, Pietro
Miro, Joan Elias
author_facet Baratella, Pietro
Miro, Joan Elias
contents The formalism of Dashen, Ma and Bernstein (DMB) expresses the thermal partition function of a system in terms of the S-matrix operator, roughly $Z(β) \propto \int dE\, e^{-βE}\,\text{Tr}\,\ln S(E),$ where $S$ denotes the full scattering operator on the asymptotic Fock space -- i.e. including all multi-particle sectors -- defined via the Lippmann-Schwinger equation. Recently we have employed this formalism to compute the free energy of flux tubes (essentially a two-dimensional theory of derivatively coupled scalars) and the two-loop $O(α_s)$ QCD thermal free energy. Moving to higher orders, it is well known that at $O(α_s^2)$ in QCD, or e.g. at $O(λ^2)$ in $λϕ^4$ theory, the free energy develops IR divergences. These IR divergences are resolved by the screening Debye mass. However, the DMB formalism expresses the free energy in terms of a trace of the S-matrix operator in the vacuum. How, then, does the Debye mass arise in this framework? In this work we address this question, thereby paving the way for higher-order applications of the DMB formalism in relativistic QFT.
format Preprint
id arxiv_https___arxiv_org_abs_2512_16466
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Thermodynamics from the S-matrix reloaded: emergent thermal mass
Baratella, Pietro
Miro, Joan Elias
High Energy Physics - Theory
High Energy Physics - Phenomenology
The formalism of Dashen, Ma and Bernstein (DMB) expresses the thermal partition function of a system in terms of the S-matrix operator, roughly $Z(β) \propto \int dE\, e^{-βE}\,\text{Tr}\,\ln S(E),$ where $S$ denotes the full scattering operator on the asymptotic Fock space -- i.e. including all multi-particle sectors -- defined via the Lippmann-Schwinger equation. Recently we have employed this formalism to compute the free energy of flux tubes (essentially a two-dimensional theory of derivatively coupled scalars) and the two-loop $O(α_s)$ QCD thermal free energy. Moving to higher orders, it is well known that at $O(α_s^2)$ in QCD, or e.g. at $O(λ^2)$ in $λϕ^4$ theory, the free energy develops IR divergences. These IR divergences are resolved by the screening Debye mass. However, the DMB formalism expresses the free energy in terms of a trace of the S-matrix operator in the vacuum. How, then, does the Debye mass arise in this framework? In this work we address this question, thereby paving the way for higher-order applications of the DMB formalism in relativistic QFT.
title Thermodynamics from the S-matrix reloaded: emergent thermal mass
topic High Energy Physics - Theory
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2512.16466