Symmetry principles of gravitational perturbations in thermal environments

Fuente: arXiv
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Autore principale: Ota, Atsuhisa
Natura: Preprint
Pubblicazione: 2025
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author Ota, Atsuhisa
author_facet Ota, Atsuhisa
contents The thermal plasma induces a plasmon-like mass shift for gravitational perturbations, which can modify their dynamics near the horizon scale in the early radiation-dominated universe. However, there are several seemingly reasonable ways to introduce this mass shift, reflecting an ambiguity in how one specifies the initial plasma state on a perturbed FLRW background. Invariance under small diffeomorphisms and Weyl rescalings singles out the (grand) canonical ensemble defined in the decoupling limit of gravitational interactions, while excluding ensembles that violate the Weyl identity, including those perturbed by the metric. Large diffeomorphisms further require the mass shift to vanish in the infrared limit. With this consistent choice, primordial tensor modes exhibit stable damping, in agreement with Weinberg's kinetic theory analysis. This cosmological example indicates a more general picture in which local equilibrium in thermal quantum field theory is not an external input but an emergent, dynamical notion.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22346
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Symmetry principles of gravitational perturbations in thermal environments
Ota, Atsuhisa
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
The thermal plasma induces a plasmon-like mass shift for gravitational perturbations, which can modify their dynamics near the horizon scale in the early radiation-dominated universe. However, there are several seemingly reasonable ways to introduce this mass shift, reflecting an ambiguity in how one specifies the initial plasma state on a perturbed FLRW background. Invariance under small diffeomorphisms and Weyl rescalings singles out the (grand) canonical ensemble defined in the decoupling limit of gravitational interactions, while excluding ensembles that violate the Weyl identity, including those perturbed by the metric. Large diffeomorphisms further require the mass shift to vanish in the infrared limit. With this consistent choice, primordial tensor modes exhibit stable damping, in agreement with Weinberg's kinetic theory analysis. This cosmological example indicates a more general picture in which local equilibrium in thermal quantum field theory is not an external input but an emergent, dynamical notion.
title Symmetry principles of gravitational perturbations in thermal environments
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2510.22346