标题： 度规仿射$R + βR^2$引力的纯剪切超动量宇宙学 显示英文标题

标题： Cosmology of Metric-Affine $R + βR^2$ Gravity with Pure Shear Hypermomentum

摘要： 在本文中，我们研究了具有超流体的度规仿射$f(R)$引力理论的宇宙学方面。该理论的运动方程是通过相对于度规和独立联络变分作用量得到的。随后，考虑一个弗里德曼-勒梅特-罗伯逊-沃尔克背景，我们在完美宇宙超流体存在的情况下推导出修改后的弗里德曼方程。特别是，我们关注$f(R)=R+\beta R^2$的特殊情况，考虑纯剪切超动量并在弱耦合极限下找到精确解。 显示英文摘要

摘要： 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-Lema\^itre-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 $f(R)=R+\beta R^2$, considering purely shear hypermomentum and finding exact solutions in the weak coupling limit.