Light bending in $F\left[g(\square)R\right]$ extended gravity theories

TL;DR

This paper investigates how light bending in extended gravity theories of the form $F[g(oxempty) R]$ behaves in the weak field limit, showing that deflection alone cannot distinguish models but may still be model-dependent after calibration.

Contribution

It demonstrates that light deflection measurements alone are insufficient to differentiate extended gravity models, highlighting the importance of calibration in observational tests.

Findings

Light deflection cannot distinguish between different $F[g(oxempty) R]$ models.

Deflection angles may be model-dependent after calibration.

Calibration of the Newton constant affects the interpretation of light bending measurements.

Abstract

We show that in the weak field limit the light deflection alone cannot distinguish between different $R + F[g(\square)R]$ models of gravity, where $F$ and $g$ are arbitrary functions. This does not imply, however, that in all these theories an observer will see the same deflection angle. Owed to the need to calibrate the Newton constant, the deflection angle may be model-dependent after all necessary types of measurements are taken into account.