Cosmology of Metric-Affine R+βR2 Gravity with Pure Shear Hypermomentum

Abstract

In this paper we study the cosmological aspects of metric-affine f(R) gravity with hyperfluid. The equations of motion of the theory are obtained by varying the action with respect to the metric and the independent connection. Subsequently, considering a Friedmann-Lemaître-Robertson-Walker background, we derive the modified Friedmann equations in the presence of a perfect cosmological hyperfluid. Especially, we focus on the particular case in which f(R)=R+βR2, considering purely shear hypermomentum and finding exact solutions in the weak coupling limit.