Investigation of Mach cones and the corresponding two-particle correlations in a microscopic transport model

Abstract

We investigate the evolution Mach cones in ultra-relativistic heavy-ion collisions within a microscopic transport model. Using smooth initial conditions and central collisions the jet-medium interaction is studied using highly-energetic jets and various values of the shear viscosity over entropy density ratio, η/s, of the matter. We observe the formation of Mach cones for small shear viscosity over entropy density ratio, η/s, while for larger values of η/s the characteristic structures smear out and eventually vanish. We extract the final azimuthal two-particle correlation from the final gluon distribution. A double-peak structure shows up if, in a single event, the jet propagates in the direction opposite to the radial flow. This indicates that the contribution from the head shock and from the diffusion wake is superimposed by the radial flow and the contribution of the Mach-cone wings can show up. Considering the superposition of many different jet paths in a central heavy-ion collision, a double-peak structure also appears. The double-peak structure then originates mostly from a superposition of deflected jet-induced Mach cones with the contribution originating from head shock and diffusion wake. A large value of the shear viscosity over entropy density ratio destroys the double-peak structure for any scenario.