Transverse Momentum Differential Global Analysis of Heavy-Ion Collisions

The understanding of heavy ion collisions and its quark-gluon plasma (QGP) 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 pPb collisions. We do this in a global model fit including a free streaming prehydrodynamic phase with variable velocity v(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 QGP bulk viscosity is small and even consistent with zero.

Automated summary

Understanding heavy ion collisions and the formation of quark-gluon plasma (QGP) requires a complex interplay of rich physics based on experimental data. By comparing the transverse momentum dependence of identified particles in PbPb and pPb collisions, this study shows different physical characteristics in the QGP formation process. Introducing a free streaming velocity variable in a global model fit widens the scope of initial conditions, while varying three second order transport coefficients during the hydrodynamic phase.