Improved Bethe-Heitler formula

TL;DR

This paper reveals a significant, previously overlooked increase in the bremsstrahlung cross section at high energies, with implications for astrophysics and electromagnetic cascade modeling.

Contribution

The authors derive new formulas showing an anomalous increment in bremsstrahlung and pair creation cross sections at high energies, challenging existing QED models.

Findings

Identified a large increment in bremsstrahlung cross section at high energies.

Demonstrated the effect also occurs in electron-positron pair creation.

Proposed astrophysical tests for the effect using atmospheric cascades.

Abstract

The Bethe-Heitler formula describes bremsstrahlung and it's a typical and important example in quantum electromagnetic dynamics (QED). This formula is widely applied in many branches of physics and astrophysics. We find that the integrated bremsstrahlung cross section at the static approximation and high energy limit has an unexpected big increment, which is missed by previous bremsstrahlung theory. This anomalous effect also exists in electron-positron pair creation. We derive the relating formulas and point out that electromagnetic cascades at the top of atmosphere can test this effect.