COLLECTIVE AZIMUTHAL ALIGNMENT IN RELATIVISTIC HEAVY ION REACTIONS

Abstract
The collective azimuthal alignment of charged particles is observed inside of two groups of particles, one emitted to the backward and one emitted to the forward hemisphere in the center of mass of symmetric heavy ion collisions. Whereas for Ca+Ca collisions no effect is observed, the alignment is present for Nb+Nb, and is even more pronounced for Au+Au. There exists also a distinct multiplicity and energy dependence of this collective azimuthal alignment.