We propose a new method of investigating the space-time evolution of meson production in heavy ion collisions, by making use of spectator-induced 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: - large distortions of charged meson spectra and ratios ($\pi^+/\pi^−$, $K^+/K^−$), - azimuthal anisotropies in charged meson production. In our approach, these effects can be computed numerically by means of a high-statistics Monte Carlo simulation, using the distance between the meson formation zone and the spectator system as (unique) free parameter. Our simulation correctly describes: - the very sizeable distortion of $\pi^+/\pi^−$ ratios in peripheral Pb+Pb collisions at top SPS energy, known from NA52 [1] and NA49 [2] experiments; - the Coulomb effect on azimuthal anisotropies observed for $\pi^+$ and $\pi^-$ mesons in Au+Au collisions at lower RHIC energy, known from data recently reported by the STAR Collaboration [3]. We also predict large azimuthal anisotropies for positive pions at target and beam rapidities, in agreement with data from the WA98 experiment [4], and a very large Coulomb distortion of $K^+/K^−$ ratios at high values of $x_F$ [5]. In all the cases studied above we find that spectator-induced Coulomb effects offer sensitivity to the position of the meson formation zone with respect to the spectator system. Therefore, we conclude that these effects can serve as a new tool to investigate the space-time evolution of meson production, and the dynamics of the heavy ion collision. More details on this work can be found in [6,7].

[1] G. Ambrosini et al. (NA52 Collaboration), New Jour. Phys. 1 (1999) 23. [2] A. Rybicki, PoS(EPS-HEP 2009) 031. [3] L. Adamczyk et al. (STAR Collaboration), arXiv:1401.3043 [nucl-ex]. [4] H. Schlagheck (WA98 Collaboration), Nucl. Phys. A 663 (2000) 725. [5] A. Rybicki, Acta Phys. Polon. B42 (2011) 867. [6] A. Rybicki and A. Szczurek, Phys. Rev. C 75, 054903 (2007), [nucl-th/0610036], [7] A. Rybicki and A. Szczurek, Phys. Rev. C 87, 054909 (2013), arXiv:1303.7354 [nucl-th].