Bremsstrahlung Dileptons in Ultra-relativistic Heavy Ion Collisions
  We consider production of dilepton pairs through coherent electro-magnetic radiation during nuclear collisions. We show that the number of pairs produced through bremsstrahlung is about two orders of magnitude smaller than the yield measured by the CERES collaboration. Therefore, coherent bremsstrahlung can be ruled out as an explanation for the observed enhancement of low mass dileptons in CERES and HELIOS. 
J. Jalilian-Marian and V. Koch (LBNL)