2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/180773We estimate the electromagnetic effect of the spectator charge on the momentum spectra of charged pions produced in peripheral Pb+Pb collisions at SPS energies. We find a large effect which results in strongly varying structures in the $x_F$ dependence of the $π^+/π^-$ ratio, especially at low transverse momenta where a deep valley in the above ratio is predicted at $x_F \sim$ 0.15 -- 0.20. The effect depends on initial conditions. Thus, it provides new information on the space and time evolution of the non-perturbative pion creation process.a talk presented by A.Szczurek at the international conference Quark Matter 2006, Shanghai, November 2006Nuclear TheoryHigh Energy Physics - Phenomenologytext