Revisiting heavy ion collisions under the influence of strong magnetic fields

Full text: The quark-gluon plasma (QGP) phase refers to matter where quarks and gluons are believed to be deconfined and it probably takes place at temperatures of the order of 150 to 170 MeV. In large colliders around the world (RHIC/BNL, ALICE/CERN, GSI, etc), physicists are trying to convert hadronic matter at these order of temperatures into QGP by looking at non-central heavy ion collisions. Possible experiments towards this search are Au-Au collisions at RHIC/BNL and Pb-Pb collisions at SPS/CERN, where the hadron abundances and particle ratios are used in order to determine the temperature and baryonic chemical potential of the possibly present hadronic matter-QGP phase transition. The magnetic fields involved in heavy-ion collisions, although time dependent and short-lived, can reach intensities higher than the ones considered in magnetars, around 1.7 x 1019 to 1020 Gauss. In fact, the densities related to the chemical potentials obtained within the relativistic models framework developed in previous works are very low (of the order of 10-3 fm-3). At these densities the nuclear interactions are indeed very small and this fact made us consider the possibility of free Fermi and Boson gases under the influence of strong magnetic fields. We investigate the effects of magnetic fields of the order of 1018, 1019 and 1020 G through a χ2 fit to some data sets of the STAR experiment. Our results shown that a field of the order of 1019 G can produce a much better fit to the experimental data than the calculations without magnetic fields. (author)