Coherent electromagnetic processes in relativistic heavy ion collisions

Using the strong electromagnetic fields in peripheral heavy ion collisions gives rise to a number of interesting possibilities of applications in both photon-photon and photon-hadron physics. We look at the theoretical foundations of the equivalent photon approximation and the specific problems in the heavy ion case. The interesting physics processes that can be studied in this way are outlined. Electron positron pair production plays a special role. We look at multiple pair production and Coulomb corrections as typical strong field effects. But electron positron pair production is also an important loss process and has some practical applications.