A transverse momentum differential global analysis of Heavy Ion Collisions

Govert Nijs, Wilke van der Schee, Umut Gürsoy, Raimond Snellings

Published 2020-10-28Version 1

The understanding of heavy ion collisions and its quark-gluon plasma formation requires a complicated interplay of rich physics in a wealth of experimental data. In this work we compare for identified particles the transverse momentum dependence of both the yields and the anisotropic flow coefficients for both PbPb and $p$Pb collisions. We do this in a global model fit including a free streaming prehydrodynamic phase with variable velocity $v_\text{fs}$, thereby widening the scope of initial conditions. During the hydrodynamic phase we vary three second order transport coefficients. The free streaming velocity has a preference slightly below the speed of light. In this extended model the bulk viscosity is small and even consistent with zero.