Eur. Phys. J. C (2008) 58: 281-289
https://doi.org/10.1140/epjc/s10052-008-0773-5

Regular Article - Theoretical Physics

Revisiting unitarity corrections for electromagnetic processes in collisions of relativistic nuclei

¹ Max-Planck-Institut für Kernphysik, Postfach 10 39 80, 69029, Heidelberg, Germany
² Institut für Theoretische Physik, Philosophenweg 16, 69120, Heidelberg, Germany
³ Institut für Physik, Universität Basel, Klingelbergstr. 82, 4056, Basel, Switzerland
⁴ ABB Switzerland Ltd., Corporate Research, Segelhof 1K, 5405, Baden, Switzerland
⁵ Novosibirsk State University, Pirogova 2, 630090, Novosibirsk, Russia

^* e-mail: serbo@math.nsc.ru

Received: 25 July 2008
Published online: 22 October 2008

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 a light-by-light scattering block between colliding nuclei. We obtain improved results for the corrections to e ⁺  e ⁻ and μ ⁺ μ ⁻ pair production as well as new results for unitarity corrections to the production of photons via virtual Compton and virtual Delbrück scattering. These corrections can be numerically large; e.g., the μ ⁺ μ ⁻ pair production cross section is reduced by about 50% and nuclear bremsstrahlung by about 15÷20%.