A Resummed Hydrodynamic Description of Relativistic Heavy-ion Collisions

TL;DR

This paper presents a new resummed hydrodynamic approach for modeling relativistic heavy-ion collisions, ensuring causality and stability while accurately capturing viscous effects, and assesses its impact on observable predictions.

Contribution

Introduces a resummed hydrodynamic scheme that incorporates nonlinear corrections and enforces causality, improving modeling of viscous effects in relativistic heavy-ion collisions.

Findings

The scheme reduces to standard hydrodynamics when viscous stresses are small.

Nonlinear corrections keep viscous stresses within tunable bounds.

Event simulations quantify uncertainties in flow observables.

Abstract

We introduce a resummed hydrodynamic scheme for evolving the viscous stress tensors in relativistic viscous hydrodynamics, based on which the necessary non-linear causality conditions can be imposed. When the magnitudes of the shear and bulk viscous stress tensors are small relative to the ideal part energy-momentum tensor, this new resummed scheme reduces to the standard second-order relativistic hydrodynamic theories. Nontrivial nonlinear corrections from high-order gradient terms retain the sizes of shear and bulk viscous stress tensors within tunable maximum allowed values. We perform event-by-event simulations for Pb+Pb and p+Pb collisions at 5.02 TeV to quantify the theoretical uncertainties from this resummed scheme on final-state flow observables.