Unimodular Gravity with Arbitrary Diffusion Function: A Dynamical System Reconstruction Approach
Abstract
We investigate cosmological diffusion models in unimodular gravity within a dynamical systems reconstruction framework. By treating the logarithmic slope of the diffusion sector as an invertible dynamical variable, the diffusion function can be systematically reconstructed from the phase-space structure of the cosmological evolution. Under these conditions, we determine the physically admissible fixed points of the system, identifying novel matter--diffusion scaling solutions associated with power-law diffusion sectors, as well as purely diffusion-dominated configurations capable of driving late-time accelerated expansion without requiring an explicit cosmological constant term. The local behavior around the fixed points is then extended to the full cosmological evolution, providing a framework to explore the global implications of diffusion cosmologies. Beyond the asymptotic fixed-point structure, we further develop a reconstruction formalism based on the dynamical evolution of the diffusion slope, allowing for trajectories interpolating between different diffusion regimes during the cosmic history. Our results establish a systematic framework for constructing and classifying viable diffusion cosmologies in unimodular gravity directly from the phase-space dynamics.
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BibTeX
@misc{gomez2026unimodular,
title = {{Unimodular Gravity with Arbitrary Diffusion Function: A Dynamical System Reconstruction Approach}},
author = {Gabriel Gómez and Guillermo Palma and Norman Cruz},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.00201},
eprint = {2609.00201},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.00201},
}
RIS
TY - UNPB
TI - Unimodular Gravity with Arbitrary Diffusion Function: A Dynamical System Reconstruction Approach
AU - Gabriel Gómez
AU - Guillermo Palma
AU - Norman Cruz
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.00201
UR - https://arxiv.org/abs/2609.00201
AB - We investigate cosmological diffusion models in unimodular gravity within a dynamical systems reconstruction framework. By treating the logarithmic slope of the diffusion sector as an invertible dynamical variable, the diffusion function can be systematically reconstructed from the phase-space structure of the cosmological evolution. Under these conditions, we determine the physically admissible fixed points of the system, identifying novel matter--diffusion scaling solutions associated with power-law diffusion sectors, as well as purely diffusion-dominated configurations capable of driving late-time accelerated expansion without requiring an explicit cosmological constant term. The local behavior around the fixed points is then extended to the full cosmological evolution, providing a framework to explore the global implications of diffusion cosmologies. Beyond the asymptotic fixed-point structure, we further develop a reconstruction formalism based on the dynamical evolution of the diffusion slope, allowing for trajectories interpolating between different diffusion regimes during the cosmic history. Our results establish a systematic framework for constructing and classifying viable diffusion cosmologies in unimodular gravity directly from the phase-space dynamics.
ER -