Running vacuum and H^4-inflation
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866916672421494784 |
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| author | Peracaula, Joan Solà Moreno-Pulido, Cristian González-Fuentes, Alex |
| author_facet | Peracaula, Joan Solà Moreno-Pulido, Cristian González-Fuentes, Alex |
| contents | Recent studies of QFT in cosmological spacetime indicate that the speeding up of the present universe may not just be associated with a rigid cosmological term but with a running one that evolves with the expansion rate: $Λ=Λ(H)$. This running is inherited from the cosmic evolution of the vacuum energy density (VED), $ρ_{\rm vac}$, which is sensitive to quantum effects in curved spacetime that ultimately trigger that running. The VED is a function of the Hubble rate and its time derivatives: $ρ_{\rm vac}=ρ_{\rm vac}(H, \dot{H},\ddot{H},...)$. Two nearby points of the cosmic evolution during the FLRW epoch are smoothly related as $δρ_{\rm vac}\sim {\cal O}(H^2)$. In the very early universe, in contrast, the higher powers of the Hubble rate take over and bring about a period of fast inflation. They originate from quantum effects on the effective action of vacuum, which we compute. Herein we focus on the lowest possible power for inflation to occur: $H^4$. During the inflationary phase, $H$ remains approximately constant and very large. Subsequently, the universe enters the usual FLRW radiation epoch. This new mechanism (`RVM-inflation') is not based on any supplementary `inflaton' field, it is fueled by pure QFT effects on the dynamical background and is different from Starobinsky's inflation, in which $H$ is never constant. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_01041 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Running vacuum and H^4-inflation Peracaula, Joan Solà Moreno-Pulido, Cristian González-Fuentes, Alex General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology High Energy Physics - Theory Recent studies of QFT in cosmological spacetime indicate that the speeding up of the present universe may not just be associated with a rigid cosmological term but with a running one that evolves with the expansion rate: $Λ=Λ(H)$. This running is inherited from the cosmic evolution of the vacuum energy density (VED), $ρ_{\rm vac}$, which is sensitive to quantum effects in curved spacetime that ultimately trigger that running. The VED is a function of the Hubble rate and its time derivatives: $ρ_{\rm vac}=ρ_{\rm vac}(H, \dot{H},\ddot{H},...)$. Two nearby points of the cosmic evolution during the FLRW epoch are smoothly related as $δρ_{\rm vac}\sim {\cal O}(H^2)$. In the very early universe, in contrast, the higher powers of the Hubble rate take over and bring about a period of fast inflation. They originate from quantum effects on the effective action of vacuum, which we compute. Herein we focus on the lowest possible power for inflation to occur: $H^4$. During the inflationary phase, $H$ remains approximately constant and very large. Subsequently, the universe enters the usual FLRW radiation epoch. This new mechanism (`RVM-inflation') is not based on any supplementary `inflaton' field, it is fueled by pure QFT effects on the dynamical background and is different from Starobinsky's inflation, in which $H$ is never constant. |
| title | Running vacuum and H^4-inflation |
| topic | General Relativity and Quantum Cosmology Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology High Energy Physics - Theory |
| url | https://arxiv.org/abs/2503.01041 |