Multipole decomposition of potentials in relativistic heavy ion collisions

In relativistic heavy ion collisions an exact multipole decomposition of the Lorentz transformed time dependent Coulomb potentials in a coordinate system with equal constant, but opposite velocities of the ions, is obtained for both zero and different from zero impact parameter. The case of large values of $\gamma$ and the gauge transformation of the interaction removing both the $\gamma$ dependence and the $\ln b$ dependence are also considered.