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Photon-Photon and Photon-Hadron Physics at Relativistic Heavy Ion Colliders

Due to the coherence of all the protons in a nucleus, there are very strong electromagnetic fields of short duration in relativistic heavy ion collisions. They give rise to quasireal photon-photon and photon-nucleus collisions with a large flux. RHIC will begin its experimental program this year and such types of collisions will be studied experimentally at the STAR detector. RHIC will have the highest flux of (quasireal) photons up to now in the GeV region. At the LHC the invariant mass range available in gamma-gamma-interactions will be of the order of 100 GeV, i.e., in the range currently available at LEP2, but with a higher gamma-gamma-luminosity. Therefore one has there also the potential to study new physics. (Quasireal) photon-hadron (i.e., photon-nucleus) interactions can be studied as well, similar to HERA, at higher invariant masses. Vector mesons can be produced coherently through photon-Pomeron and photon-meson interactions in exclusive reactions such as A+A -> A+A+V, where A is the heavy ion and V=rho,omega,phi or J/Psi.