Aleksander Kozak

Due to certain limitations of general relativity, one might be inclined to consider modifications to the theory in order to provide a more accurate model of gravitational phenomena. One possible approach is to extend the Einstein-Hilbert action by introducing higher-order terms. Another possibility is to modify the underlying geometry of spacetime, for example, by decoupling the metric structure from the affine structure of spacetime, which leads to the so-called metric-affine framework. In our analysis, we focus on a simple model that introduces quadratic curvature corrections, constructed from the metric tensor and independent connection. We then analyze the behavior of the theory in two distinct regimes: late-time cosmic acceleration and the internal structure of small-scale astrophysical objects, such as planets, due to the fact that modified theories of gravity often alter the weak-field limit. We compare the results of these two methods of constraining models and discuss implications for testing more complicated modified theories of gravity.