New results on Coulomb effects in meson production in relativis- tic heavy ion collisions

Abstract. We propose a new method of investigating the space-time evolution of meson production in heavy ion collisions, by making use of spectator-induced electromagnetic (“Coulomb”) effects. The presence of two nuclear remnants (“spectator systems”) in the non-central collision generates a strong Coulomb field, which modifies the trajectories of charged final state hadrons. This results in charge-dependent azimuthal anisotropies in final state meson emission. In our approach, this effect can be computed numerically by means of a high-statistics Monte Carlo simulation, using the distance between the me-son formation zone and the spectator system as free parameter. Our simulation correctly describes the electromagnetic effect on azimuthal anisotropies observed for π+ and π− mesons in Au+Au collisions at lower RHIC energy, known from data recently reported by the STAR Collaboration. Similarly to our earlier studies of spectator-induced electro-magnetic effects, also in the present study we find that these effects offer sensitivity to the position of the meson formation zone with respect to the spectator system. Therefore, we conclude that they can serve as a new tool to investigate the space-time evolution of meson production, and the dynamics of the heavy ion collision.