Can vacuum decay in our Universe?
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We take a phenomenological approach to study the cosmological evolution of decaying vacuum cosmology ($\Lambda(t)$CDM) based on a simple assumption about the form of the modified matter expansion rate. In this framework, almost all the current vacuum decaying models can be unified in a simple manner. We argue that the idea of letting vacuum decay to resolve the fine-tuning problem is inconsistent with cosmological observations. We also discuss some issues in confronting $\Lambda(t)$CDM with observation. Using the effective equation of state formalism, we indicate that $\Lambda(t)$CDM is a possible candidate for phantom cosmology. Moreover, confronted with a possible trouble of effective equation of state formalism, we construct the effect dark energy density. Finally, we discuss the evolution of linear perturbation.
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Cited by 2 Pith papers
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Generalizing the CPL Parametrization through Dark Sector Interaction
Dynamical couplings in interacting dark energy models reduce deviations from LambdaCDM to 1.3-1.5 sigma and yield no Bayesian preference over the standard model.
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Generalizing the CPL Parametrization through Dark Sector Interaction
Generalized interacting dark energy models with constant or dynamical couplings yield analytical density expressions but are not preferred over LambdaCDM by Bayesian evidence from DESI, Pantheon+, and CMB data.
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