Inflaton and metric fluctuations in the early universe from a 5D vacuum state

Abstract

In this letter we complete a previously introduced formalism to study the gauge-invariant metric fluctuations from a noncompact Kaluza-Klein theory of gravity, to study the evolution of the early universe. The evolution of both, metric and inflaton field fluctuations are reciprocally related. We obtain that <\delta\rho/\rho_b$dependsonthecouplingof$\Phi$with$\delta\phi$andthespectralindexofitsspectrumis:$0.9483 < n_1 < 1$.

Comments: version accepted in Phys. Lett. B