Net baryon diffusion in fluid dynamic simulations of relativistic heavy-ion collisions

TL;DR

This paper develops a hybrid hydrodynamic and transport model to study the effects of net baryon diffusion on observables in relativistic heavy-ion collisions, providing new insights into baryon transport phenomena.

Contribution

It introduces a fully integrated framework incorporating net baryon diffusion into hydrodynamics and hadronic transport for the first time.

Findings

Net baryon diffusion significantly affects hadronic observables.

The hadronic transport phase influences particle spectra and flow.

Phenomenological effects of baryon diffusion are demonstrated for the first time.

Abstract

A hybrid (hydrodynamics + hadronic transport) theoretical framework is assembled to model the bulk dynamics of relativistic heavy-ion collisions at energies accessible in the Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider (RHIC) and the NA61/SHINE experiment at CERN. The system's energy-momentum tensor and net baryon current are evolved according to relativistic hydrodynamics with finite shear viscosity and non-zero net baryon diffusion. Our hydrodynamic description is matched to a hadronic transport model in the dilute region. With this fully integrated theoretical framework, we present a pilot study of the hadronic chemistry, particle spectra, and anisotropic flow. Phenomenological effects of a non-zero net-baryon current and its diffusion on hadronic observables are presented for the first time. The importance of the hadronic transport phase is also investigated.