Strong-field effect for the process of photon emission in collisions of relativistic nuclei at RHIC and LHC

Virtual Delbrück scattering in heavy-ion collisions contributes to the emission of photons. Specifically, the elastic scattering of an equivalent photon emitted by a nucleus in the Coulomb field of an incoming nucleus can lead to the emission of a photon in the collision of ultra-relativistic nuclei Z1Z2 → Z1Z2γ. The discussed process has no infrared divergence. The total cross section obtained is 14 barn for the Au–Au collisions at the RHIC collider and 50 barn for the Pb–Pb collisions at the LHC collider. These cross sections are considerably larger than those for ordinary nuclear bremsstrahlung in the same photon energy range.