Strong suppression of Coulomb corrections to the cross section of e+e- pair production in ultrarelativistic nuclear collisions

TL;DR

This paper calculates Coulomb corrections to electron-positron pair production in ultrarelativistic nuclear collisions, revealing significant suppression that explains why experimental deviations from the Born approximation were not observed.

Contribution

It introduces a next-to-leading approximation calculation showing strong suppression of Coulomb corrections in high-energy nuclear collisions.

Findings

Coulomb corrections are significantly reduced at high energies.

Suppression occurs even at large Lorentz factors.

Results align with experimental observations at SPS.

Abstract

The Coulomb corrections to the cross section of $e^+e^-$ pair production in ultrarelativistic nuclear collisions are calculated in the next-to-leading approximation with respect to the parameter $L=\ln \gamma_A\gamma_B$ ($\gamma_{A,B}$ are the Lorentz factors of colliding nuclei). We found considerable reduction of the Coulomb corrections even for large $\gamma_A\gamma_B$ due to the suppression of the production of $e^+e^-$ pair with the total energy of the order of a few electron masses in the rest frame of one of the nuclei. Our result explains why the deviation from the Born result were not observed in the experiment at SPS.