Wednesday, June 5, 2013

1306.0591 (E. L. D. Perico et al.)

Complete Cosmic History with a dynamical Lambda(H) term    [PDF]

E. L. D. Perico, J. A. S. Lima, Spyros Basilakos, Joan Sola
In the present main-stream cosmology, matter and spacetime emerged from a singularity and evolved through four distinct periods: early inflation, radiation, dark matter and late time inflation (driven by dark energy). During the radiation and dark matter dominated stages the universe is decelerating while the early and late time inflations are accelerating stages. A possible connection between the accelerating periods remains unknown, and, even more intriguing, the best dark energy candidate powering the present accelerating stage (Lambda-vacuum) is plagued with the cosmological constant and coincidence puzzles. Here we propose an alternative solution for such problems based on a large class of time-dependent vacuum energy density models in the form of power series of the Hubble rate, Lambda=Lambda (H). The proposed class of Lambda(H)-decaying vacuum model provides: i) an alternative mechanism for inflation (beyond the usual inflaton models, some of them in serious trouble after the recent PLANCK release of accurate cosmic data), (ii) a natural mechanism for graceful exit, which is universal for the whole class of models; iii) the currently accelerated expansion of the universe, iv) a mild dynamical dark energy at present; and v) a final de Sitter stage. Remarkably, the late time cosmic expansion history of our class of models is very close to the concordance LCDM model, but above all it also furnishes the necessary smooth link between the initial and final de Sitter stages through the radiation and matter dominated epochs.
View original: http://arxiv.org/abs/1306.0591

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