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arXiv · 2607.19494

The silent dark sector: a field-theory approach to unified dark fluids with vanishing speed of sound

Javier de Cruz Pérez·Darío Jaramillo-Garrido·Antonio L. Maroto·Prado Martín-Moruno
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Abstract

We introduce a novel class of field-theory models that provide a unified description of the dark sector as a single perfect fluid with vanishing sound speed. These models also admit the interpretation of cold dark matter interacting with vacuum energy while avoiding any phantom behavior and including standard $\Lambda$CDM as a particular case. Built upon a single scalar field invariant under transverse diffeomorphisms, the framework naturally implements the constraints imposed in the so called mimetic models. We analyze a particular simple example exhibiting an effectively evolving dark energy and find that it can reproduce the DESI best-fit CPL evolution with the same number of free parameters.

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Javier de Cruz Pérez, Darío Jaramillo-Garrido, Antonio L. Maroto, Prado Martín-Moruno. 2026-07-21. The silent dark sector: a field-theory approach to unified dark fluids with vanishing speed of sound. https://arxiv.org/abs/2607.19494

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