2018

Eskola, Kari; Niemi, Harri; Paatelainen, R.; Tuominen, K.

We present the event-by-event next-to-leading-order perturbative-QCD + saturation + viscous hydrodynamics (EKRT) model predictions for the centrality dependence of the charged hadron multiplicity in the pseudorapidity interval |η|≤0.5, and for the centrality dependence of the charged hadron flow harmonics vn{2} obtained from two-particle cumulants, in √sNN=5.44 TeV Xe+Xe collisions at the CERN Large Hadron Collider. Our prediction for the 0–5 % central charged multiplicity is dNch/dη=1218±46. We also predict vn{2} in Xe+Xe collisions to increase more slowly from central towards peripheral collisions than those in a Pb+Pb system. We find that at 10,⋯,50% centralities v2{2} is smaller and v3{2} is larger than in the Pb+Pb system while v4{2} is of the same magnitude in both systems. We also find that the ratio of flow harmonics in Xe+Xe collisions and in Pb+Pb collisions shows a slight sensitivity to the temperature dependence of the shear-viscosity–to–entropy ratio. As we discuss here, the new nuclear mass-number systematics especially in the flow harmonics serves as a welcome further constraint for describing the space-time evolution of a heavy-ion system and for determining the shear viscosity and other transport properties of strongly interacting matter.