BSQ Conserved Charges in Relativistic Viscous Hydrodynamics solved with Smoothed Particle Hydrodynamics

TL;DR

This paper introduces a new relativistic viscous hydrodynamics code, CCAKE, using SPH formalism to conserve BSQ charges and incorporates lattice QCD-based EoS, with initial conditions from ICCING, analyzing charge correlations and their effects on particle multiplicities and flow.

Contribution

The paper presents a novel 2+1 relativistic viscous hydrodynamics code that conserves BSQ charges using SPH and integrates lattice QCD EoS with initial conditions from ICCING.

Findings

BSQ fluctuations remain finite during evolution.

ICCING has minimal effect on collective flow for single particles.

ICCING influences flow when considering pairs of particles.

Abstract

Conservation laws play a crucial role in the modeling of heavy-ion collisions, including the those for charges such as baryon number (B), strangeness (S), and electric charge (Q). In this study, we present a new 2+1 relativistic viscous hydrodynamic code called CCAKE which uses the Smoothed Particle Hydrodynamics (SPH) formalism to locally conserve BSQ charges, together with an extended description of the multi-dimensional equation of state (EoS) obtained from lattice Quantum Chromodynamics. Initial conditions for CCAKE are supplied by the ICCING model, which samples gluon splittings into quark anti-quark pairs to generate the initial BSQ charge distributions. We study correlations between the BSQ charges and find that local BSQ fluctuations remain finite during the evolution, with corresponding chemical potentials of ($\sim100$--$200 \,\rm MeV$) at freeze-out. We find that our framework produces reasonable multiplicities of identified particles and that ICCING has no significant effect on the collective flow of all charged particles nor of identified particles when only one particle of interest is considered. However, we show specifically for Pb+Pb collisions at the LHC $\sqrt{s_{NN}}=5.02$ TeV that ICCING does have an effect on collective flow of identified particles if two particles of interest are considered.