Seminarium Teorii Względności i Grawitacji

One of the mostly debated topic in modern cosmology is model building for inflation. Recent Planck data seem to favor simple models, amongst them there is the Starobinsky model based on the modification of the gravitational action. Its characteristic feature is the presence of the Ricci scalar squared term. It is often assumed that such a term could be generated by the loop correction of the matter sector. During the presentation I will show by explicit calculations how to obtain such a term in the framework of quantum field theory in curved spacetime. Surprisingly, the obtained results seem to indicate that the attained inflationary action leads to an incorrect model of inflation.