Comunicazione
4D cosmological consequences of Brans-Dicke theory from 5D scalar vacuum.
Troisi A., Lambiase G.
$5D$ Brans-Dicke (BD) theory is discussed in the framework of (gravitational) baryogenesis and primordial light element formation. Such a cosmological model could represent a suitable scheme to explain the present cosmic accelerated expansion without recurring to matter fields in $5D$ or dark energy in $4D$ if one assumes the scheme of Kaluza-Klein induced-matter theory. In this approach after the $5D$ to $4D$ reduction, a space-matter tensor related with BD-scalar field and higher-dimensional counter-terms arises on shell playing the role of a new ingredient on the four-dimensional hypersurfaces orthogonal to the extra coordinate. Since the FRW cosmological equations admit a power law solution of the scale factor, $a(t)\sim t^\alpha$, one can constrain the exponential factor $\alpha$ by using the present bounds on the matter-antimatter asymmetry in the Universe and Big Bang Nucleosyntheis (BBN). A possible connection with Dark Matter relic abundance is also discussed.