Preinflation without matter from f(R)-Extended General Relativity

Starting with a f(R)=ReR6M2-Extended General Relativity with physical sources included, we develop a preinflationary model where the background dynamics is driven by curvaton fluctuations, which are the trace of gravitational waves. We explore two possible solutions with the same equation of state: P/ρ=−1, for M2=±Mp2. We obtain the conditions for which a preinflationary scenario might have been possible due to the curvaton fluctuations effect on the background dynamics in absence of background matter fields, and we study the dynamics for gravitational waves. The ln(k)-spectrum of the scalar curvature on the extended manifold is obtained.