Multiple electron-positron pair production in relativistic heavy-ion collisions: A strong-field effect

First-order calculations of ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ pair production in relativistic heavy-ion collisions exceed unitarity for heavy nuclei and γ values of the order of γ>1000, at impact parameters of the order of the Compton wavelength of the electron. It is shown how unitarity can be restored by using the sudden approximation, which is very appropriate for this kind of collision. It is found that the probability of creating N ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ pairs in a single collision is given by a Poisson distribution. Such strong-field effects will occur and can in principle be studied with relativistic heavy ions in the planned colliders like the relativistic heavy-ion collider at Brookhaven National Laboratory or the large hadron collider at CERN.