Exploring theoretical uncertainties in the hydrodynamic description of relativistic heavy-ion collisions

We explore theoretical uncertainties in the hydrodynamic description of relativistic heavy-ion collisions by examining full nonlinear causality conditions and quantifying second-order transport coefficients' role on flow observables. The impose physical constraints maximum allowed values inverse Reynolds numbers during evolution. Including additional gradient terms Denicol-Niemi-Moln\'ar-Rischke (DNMR) theory significantly shrinks casual regions compared to those Israel-Stewart hydrodynamics. For $\mathrm{Au}+\mathrm{Au}$ collisions, we find variations observables are small with without imposing necessary conditions, suggesting a robust extraction quark-gluon plasma's coefficients previous model-to-data comparisons. However, sizable sensitivity is present $p+\mathrm{Au}$ which poses challenges study systems' collectivity.