66 research outputs found
Lattice-QCD-based equations of state at finite temperature and density
The equation of state (EoS) of QCD is a crucial input for the modeling of
heavy-ion-collision (HIC) and neutron-star-merger systems. Calculations of the
fundamental theory of QCD, which could yield the true EoS, are hindered by the
infamous Fermi sign problem which only allows direct simulations at zero or
imaginary baryonic chemical potential. As a direct consequence, the current
coverage of the QCD phase diagram by lattice simulations is limited. In these
proceedings, two different equations of state based on first-principle lattice
QCD (LQCD) calculations are discussed. The first is solely informed by the
fundamental theory by utilizing all available diagonal and non-diagonal
susceptibilities up to in order to reconstruct a full
EoS at finite baryon number, electric charge and strangeness chemical
potentials. For the second, we go beyond information from the lattice in order
to explore the conjectured phase structure, not yet determined by LQCD methods,
to assist the experimental HIC community in their search for the critical
point. We incorporate critical behavior into this EoS by relying on the
principle of universality classes, of which QCD belongs to the 3D Ising Model.
This allows one to study the effects of a singularity on the thermodynamical
quantities that make up the equation of state used for hydrodynamical
simulations of HICs. Additionally, we ensure that these EoSs are valid for
applications to HICs by enforcing conditions of strangeness neutrality and
fixed charge-to-baryon-number ratio.Comment: Contribution to the 37th Winter Workshop on Nuclear Dynamics. arXiv
admin note: text overlap with arXiv:2103.0814
Thermodynamics of an updated hadronic resonance list and influence on hadronic transport
Hadron lists based on experimental studies summarized by the Particle Data
Group (PDG) are a crucial input for the equation of state and thermal models
used in the study of strongly-interacting matter produced in heavy-ion
collisions. Modeling of these strongly-interacting systems is carried out via
hydrodynamical simulations, which are followed by hadronic transport codes that
also require a hadronic list as input. To remain consistent throughout the
different stages of modeling of a heavy-ion collision, the same hadron list
with its corresponding decays must be used at each step. It has been shown that
even the most uncertain states listed in the PDG from 2016 are required to
reproduce partial pressures and susceptibilities from Lattice Quantum
Chromodynamics with the hadronic list known as the PDG2016+. Here, we update
the hadronic list for use in heavy-ion collision modeling by including the
latest experimental information for all states listed in the Particle Data
Booklet in 2021. We then compare our new list, called PDG2021+, to Lattice
Quantum Chromodynamics results and find that it achieves even better agreement
with the first principles calculations than the PDG2016+ list. Furthermore, we
develop a novel scheme based on intermediate decay channels that allows for
only binary decays, such that PDG2021+ will be compatible with the hadronic
transport framework SMASH. Finally, we use these results to make comparisons to
experimental data and discuss the impact on particle yields and spectra.Comment: 17 pages, 16 figures, 2 table
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