# All-order Coulomb corrections to Delbr\"uck scattering above the pair production threshold

## TL;DR

This paper calculates all-order Coulomb corrections to Delbruck scattering for photon energies above pair production threshold, significantly improving theoretical predictions for heavy atoms and resolving previous discrepancies with experimental data.

## Contribution

It introduces a method using the Dirac-Coulomb Green function to include Coulomb corrections to all orders in the nuclear charge parameter, enhancing accuracy for high-energy photon scattering.

## Key findings

- Coulomb corrections increase the scattering cross section by up to 50%.
- Results align theory with experimental data for plutonium.
- Highlights importance of Coulomb corrections in interpreting heavy atom scattering experiments.

## Abstract

We report calculations of Delbr\"uck scattering that include all-order Coulomb corrections for photon energies above the threshold of electron-positron pair creation. Our approach is based on the application of the Dirac-Coulomb Green function and accounts for the interaction between the virtual electron-positron pair and the nucleus to all orders in the nuclear binding strength parameter $\alpha Z$. Practical calculations are performed for the scattering of 2.754 MeV photons off plutonium atoms. We find that including the Coulomb corrections enhances the scattering cross section by up to 50% in this case. The obtained results resolve the long-standing discrepancy between experimental data and theoretical predictions and demonstrate that an accurate treatment of the Coulomb corrections is crucial for the interpretation of existing and guidance of future Delbr\"uck scattering experiments on heavy atoms.