Аңдатпа
In this paper, we investigate a scenario of variable gravity and apply it to the unified description of inflation and late-time cosmic acceleration dubbed quintessential inflation. The scalar field called ``cosmon,'' which in this model unifies both the concepts, reduces to the inflaton at early epochs. We calculate the slow-roll parameters, the Hubble parameter at the end of inflation, the reheating temperature, and the tensor-to-scalar ratio, and we demonstrate the agreement of the model with observations and the Planck data. As for the postinflationary dynamics, the cosmon tracks the background before it exits the scaling regime at late times. The scenario gives rise to the correct epoch sequence of standard cosmology, namely, radiative regime, matter phase, and dark energy. We show that the long kinetic regime after inflation gives rise to enhancement of the relic gravity wave amplitude, resulting in violation of the nucleosynthesis constraint at the commencement of the radiative regime in the case of an inefficient reheating mechanism, such as gravitational particle production. Instant preheating is implemented to successfully circumvent the problem. As a generic feature, the scenario gives rise to a blue spectrum for gravity waves on scales smaller than the comoving horizon scale at the commencement of the radiative regime.