Article

# Observational constrains on the cosmology with a decaying cosmological term

12/2006; -1:149.

Source: arXiv

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Masa-aki Hashimoto, Sep 21, 2014 Available from: Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

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**ABSTRACT:**Motivated by recent attempts to solve the cosmological constant problem, we examine the observational consequences of a vacuum energy which decays in time. In both radiation and matter dominated eras, the ratio of the vacuum to the total energy density of the universe must be small. Although the vacuum cannot provide the “missing mass” required to close the universe today, its presence earlier in the history of the universe could have important consequences. Element abundances from primordial nucleosynthesis require the ratio x = ϱvac/(ϱvac + ϱrad) ⩽ 0.1 of neutrino (or equivalent light) species to exceed Nν > 4, a case ruled out in the standard cosmological model. If the vacuum decays into low energy photons, the lack of observed spectral distortions in the microwave background gives tighter bounds, x < 4 × 10−4. In the matter-dominated era, the presence of a vacuum term may allow more time for growth of protogalactic perturbations.Nuclear Physics B 01/1987; 287(287):797-814. DOI:10.1016/0550-3213(87)90129-5 · 3.93 Impact Factor - [Show abstract] [Hide abstract]

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