Electromagnetic processes in relativistic heavy ion collisions

Abstract

Here is presented a study of the processes generated by the electromagnetic interaction in relativistic nuclear, and atomic collisions. There is nowadays a vivid interest in this field due to the construction of relativistic heavy ion accelerators. Certainly, the most important purpose of these relativistic heavy ion machines is the study of nuclear matter under extreme conditions. In central nucleus-nucleus collisions one hopes to observe new forms of nuclear matter, like the quark-gluon plasma [Lu-84, Bay-86]. On the other hand, very strong electromagnetic fields for a very short time are present in distant collisions with no nuclear contact. Such fields can also lead to interesting effects, which are discussed here. There have been many interesting theoretical and experimental developments on this subject, and new ares of research were opened. Of special interest is, e.g., the case of nuclear fragmentation. This is accomplished through the excitation of giant resonances or by direct break-up of the nuclei by means of their electromagnetic interaction. It is shown that this process can be used to study nuclear structure properties which are n not accessible by means of the traditional electromagnetic excitation at nonrelativistic energies. The creation of particles is also of interest due to the large cross sections, specially in the case of electron-positron pair creation. Although one can develop very elaborate and complicated calculations to explain the many processes originated in this way, the results can be understood in very simple terms because of our almost complete comprehension of the electromagnetic interaction. For those processes where the electromagnetic interaction plays the dominant role this is clearly a very useful tool for the investigation of the structures created by the strong interaction in the nuclei or hadrons.