New results on energy and momentum conservation in meson production for A+A collisions at SPS energies

¹ H.Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
² University of Rzeszów, Rejtana 16, 35-959 Rzeszów, Poland

^* e-mail: andrzej.rybicki@ifj.edu.pl

Published online: 1 February 2019

Abstract

We review our recent findings on electromagnetic (EM) effects in Ar+Sc and Pb+Pb collisions at CERN SPS energies, and discuss them in the context of our earlier results on the EM splitting of π⁺/π^- meson directed flow. A specific space-time picture emerges, on the basis of which we construct a simple model of the collision. Starting from local energy and momentum conservation, we nicely describe the centrality dependence of π meson rapidity distributions in Pb+Pb collisions at $\sqrt{s_{NN}}=17.3\hspace{0.17em}\text{GeV}$. We discuss the resulting implications on the role of energy and momentum conservation for the dynamics of meson production in A+A collisions. We present our conclusions on the link between the initial stages of the nuclear collision and the final state observables connected to strong and electromagnetic phenomena in charged meson emission. We also discuss the possibility to use the latter EM phenomena to obtain new insight into the spectator space-time evolution and excitation energy.