Revisiting unitarity corrections for electromagnetic processes in collisions of relativistic nuclei

TL;DR

This paper revisits unitarity corrections in electromagnetic processes during relativistic heavy-ion collisions, providing improved and new results that significantly impact cross section calculations for pair production and photon emission.

Contribution

It offers refined calculations of unitarity corrections for pair production and introduces new results for photon production processes in relativistic nuclear collisions.

Findings

Muon pair production cross section reduced by ~50%.

Nuclear bremsstrahlung decreased by 15-20%.

Unitarity corrections can be numerically significant.

Abstract

Unitarity corrections to several electromagnetic processes in collisions of relativistic heavy nuclei are considered. They are due to the unitarity requirement for the S-matrix and correspond to the exchange of light-by-light scattering block between colliding nuclei. We obtain improved results for the corrections to e+e- and mu+mu- pair production, as well as new results for unitarity corrections to the production of photons via virtual Compton and virtual Delbruck scattering. These corrections can be numerically large; e.g., the mu+mu- pair production cross section is reduced by about 50% and the nuclear bremsstrahlung by about 15 to 20%.