Analisando extensões do modelo de Starobinsky em gravidade de ordem superior

Abstract

In 1980, the Soviet physicist Alexei Starobinsky developed a cosmological model that features an accelerated expansion at the beginning of cosmic expansion, which embraces modi cations in General Relativity. Although Starobinsky's motivation was adding corrections to remove singularities occurred with Einstein's theory, his model is one of the best- t in ation theories regarding observational data nowadays. Nevertheless, new data from future projects, such as the LiteBIRD satellite and the CMB-S4 experiment, may disfavor it. Hence, extensions of it are being considered seeking shifts in parameters related to observational data. Here, three higher-order extensions of the Starobinsky model are presented: Starobinsky + R3, Starobinsky + R□R and Starobinsky + RRµνRµν (the last one is a new contribution to the literature). For this, a higher-order model whose action contains up to cubic scalars (cosmological constant not included) is developed, from which is shown that all cubic scalars relevant to in ation dynamics in background cosmology are R3, R□R and RRµνRµν.