Initial state in relativistic heavy ion collisions

Abstract

At high temperatures or densities a state of matter formed by deconfined quarks and gluons emerges: the QGP. These conditions were present in the early universe and are replicable in the laboratory through relativistic heavy ion collisions. In peripheral collisions the system seems to be sensitive to vorticity due to the large initial angular momentum. This is thought to cause polarization, which is measurable through the spin of the emitted particles. Experimental data shows asymmetry between λ and λ polarization, whose origin is not yet clear. In this paper we examine an initial state model to describe QGP evolution that applies Bjorken-like solution streak by streak in the collision transverse plane. The original model distributes energy and baryons along each streak, whereas our proposal homogeneously distributes baryons only at the extremes, while energy is kept as before. This extreme distribution has led to a new vorticity configuration that potentially could explain the observed differences between λ and λ polarization