Using a coordinate-independent impact parameter in the post-post-Newtonian light deflection formulas

TL;DR

This paper shows that using a coordinate-independent impact parameter removes large 'enhanced' terms in post-post-Newtonian light deflection formulas, leading to more accurate and consistent predictions.

Contribution

It introduces a coordinate-independent impact parameter that eliminates the 'enhanced' terms in light deflection calculations, improving the theoretical framework.

Findings

'Enhanced' terms vanish with the new impact parameter

Improved accuracy in post-post-Newtonian light deflection formulas

Clarification of impact parameter choice in gravitational lensing

Abstract

In [2] we have seen that among the post-post-Newtonian terms in the light deflection formulas there are "enhanced" ones that may become much larger than the other post-post-Newtonian terms. It is demonstrated here that these "enhanced" terms result from an inadequate choice of the impact parameter. Introducing another impact parameter, that can be considered as coordinate-independent, we demonstrate that all "enhanced" terms disappear from the formulas.