On the quasi-de sitter cosmological model of Starobinsky

Abstract

A non-singular cosmological model that permits inflation has been constructed by Starobinsky, starting from the theory with lagrangian density Image. The spectrum of density perturbations is approximately adiabatic, with amplitude δρ/ρ≈|0−4 on the scale of a galaxy, provide that mless-than-or-equals, slant5×10−6mP. We rederive this constraint via the result of Whitt, who found by conformally transforming the metric that Image can be written in the form of gravity interacting with a minimally coupled scalar field. The implications of this result for the problem of initial conditions in the universe are also discussed.