Regular Article - Theoretical Physics
Inflation and late-time acceleration in braneworld cosmological models with varying brane tension
Department of Physics, University of Hong Kong, Pok Fu Lam Road, Hong Kong, P.R. China
2 Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road, Hong Kong, P.R. China
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Published online: 3 June 2010
Braneworld models with variable brane tension λ introduce a new degree of freedom that allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We consider a thermodynamic interpretation of the varying brane tension models, by showing that the field equations with variable λ can be interpreted as describing matter creation in a cosmological framework. The particle creation rate is determined by the variation rate of the brane tension, as well as by the brane–bulk energy-matter transfer rate. We investigate the effect of a variable brane tension on the cosmological evolution of the Universe, in the framework of a particular model in which the brane tension is an exponentially dependent function of the scale factor. The resulting cosmology shows the presence of an initial inflationary expansion, followed by a decelerating phase, and by a smooth transition towards a late accelerated de Sitter type expansion. The varying brane tension is also responsible for the generation of the matter in the Universe (reheating period). The physical constraints on the model parameters, resulting from the observational cosmological data, are also investigated.
© Springer-Verlag / Società Italiana di Fisica, 2010