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wolram

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[4] arXiv:1209.2802 [pdf, ps, other]

Expansion History with Decaying Vacuum: A Complete Cosmological ScenJ. A. S. Lima, S. Basilakos, Joan So

Comments: LaTeX, 11 pages and one figure

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Extragalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

We propose a novel cosmological scenario with the space-time emerging from a pure initial de Sitter stage and subsequently evolving into the radiation, matter and dark energy dominated epochs, thereby avoiding the initial singularity and providing a complete description of the expansion history and a natural solution to the horizon problem. The model is based on a running vacuum energy density which evolves as a power series of the Hubble rate: \rho_{\Lambda}(H). The transit from the inflation into the standard radiation epoch is universal, giving a clue for a successful description of the graceful exit. The Universe is finally driven into the present slow accelerated expansion, characterized by a residual (but dynamical) vacuum energy: \rho_{\Lambda}(H)=c_0+c_2H^2. While the resulting late time cosmic history is very close to the concordance \Lambda CDM model, the new unified framework embodies a more complete past cosmic evolution than the standard cosmology