Gravitational Deflection of Vector Photons via Effective Field Theory

TL;DR

This paper uses effective field theory and advanced computational techniques to analyze how vector photons are deflected by gravity, providing insights into light bending by massive objects.

Contribution

It introduces a systematic approach employing IBP reduction and the eikonal approximation to compute gravitational deflection of vector photons in the weak field regime.

Findings

Derived explicit expressions for photon deflection angles.

Clarified the origin of differences with previous calculations.

Enhanced understanding of light-matter interactions in gravitational fields.

Abstract

Gravitational scattering of the electromagnetic field from a heavy scalar field provides a fundamental testbed for understanding the deflection of light by massive bodies. In many approaches based on effective field theory, the calculation of scattering amplitudes quickly becomes complicated due to the large number of Feynman integrals required, especially beyond leading order. In this work, we study this problem using effective field theory in the weak field approximation. We utilize Integration-By-Parts reduction techniques to precisely examine the long-range contributions governed by terms in the amplitude which are non-analytic in momentum transfer. Using geometric optics and the eikonal approximation, we derive expressions for the deflection angle and find the origin of differences relative to earlier works.