Thermal-FIST: A package for heavy-ion collisions and hadronic equation of state

Abstract

Thermal-FIST * * is a C++ package designed for convenient general-purpose physics analysis within the family of hadron resonance gas (HRG) models. This mainly includes the statistical analysis of particle production in heavyion collisions and the phenomenology of hadronic equation of state. Notable features include fluctuations and correlations of conserved charges, effects of probabilistic decay, chemical non-equilibrium, and inclusion of van der Waals hadronic interactions. Calculations are possible within the grand canonical ensemble, the canonical ensemble, as well as in mixed-canonical ensembles combining the canonical treatment of certain conserved charges with the grand-canonical treatment of other conserved charges. The package contains a fast thermal event generator, which generates particle yields in accordance with the HRG chemistry, and particle momenta based on the Blast Wave model. A distinct feature of this package is the presence of the graphical user interface frontend -QtThermalFIST -which is designed for fast and convenient general-purpose HRG model applications. Program summaryProgram Title: Thermal-FIST, version 1.2 Licensing provisions: GPLv30 Programming language: C++ Computer: any with a C++ compiler and, optionally, the Qt5 framework for the GUI frontend Operating system: cross-platform, tested on Linux Ubuntu 16.04, 18.04; Mac OS X Yosemite, Microsoft Windows 10; Android 8, 9 External routines: Eigen template library for the linear algebra routines [1], MI-NUIT2 package from CERN ROOT [2], Mersenne Twister random number generator [3], Qt5 framework [4] (for the GUI only), QCustomPlot Qt widget [5] (for the GUI only) Nature of problem:The HRG model and its various modifications constitute a common framework used for modeling of the hadronic equation of state and particle production in heavy-ion collisions. Even the simplest versions of the HRG model require careful considerations of the many details, including the resonance decay feed-down, implementation of charge conservation constraints relevant for heavy-ion collisions, chemical non-equilibrium effects. A notable extra effort is required in order to treat the fluctuations and correlations of various charges charges, which presently are being extensively studied in the heavy-ion collision experiments and lattice QCD calculations. The inclusion of hadronic interactions, modeled by an excludedvolume (EV) or a van der Waals (vdW) type framework, additionally requires a numerical solution to a system of many transcendental equations. Solution method:The Thermal-FIST package contains a class-based library which calculates relevant HRG observables for a specified setup. The setup includes a particle list, usually to be supplied with an external file, an HRG model specification (statistical ensemble, van der Waals interaction parameters, etc.), a set of thermal parameters, and conservation laws constraints. Whenever necessary, the systems of transcendental equations are solved numerically with the Broyden's method. The package includes a fitt...

Temperature and fluid velocity on the freeze-out surface from π , K , and p spectra in pp , Mazeliauskas1, Vislavicius2 2020Phys. Rev. C

“…We see that for Pb-Pb collisions the freeze-out temperature is in 152-156 MeV range and close to the chemical freezeout temperature T chem = 156.5 ± 1.5 MeV obtained by the statistical model fitted to light and multi-strange hadrons in the most central collisions [2]. Studies of centrality dependence of thermal model parameters also find weak temperature dependence, but the temperature is higher than extracted in out fits [39][40][41]. We note that in our model we use only π, K, p spectra and do not introduce baryon chemical potential, canonical suppression or strangeness undersaturation effects.…”

Entropy production in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

“…Using the implementation of the hadron resonance gas of Ref. [39] we find (N/N ch ) TF = 1.09. In the following we use N/N ch = 1.115 ± 0.03, i.e., we take the average of the two results as central value and the difference as a measure of the uncertainty.…”

Tsallis-thermometer: a QGP indicator for large and small collisional systems

“…In this section the thermodynamical variables are calculated for each hadron species and for each investigated system. The results of the integrations defined by equations (12) With solid curves several theoretical models are shown, including lattice QCD calculations (Budapest -Wuppertal, with red [129] and HotQCD, with green [130]), a hadron resonance gas model (Thermal-FIST, with orange [131]), a Polyakov constituent quark-meson model (Kovács -Szép -Wolf, with blue [132]), and an effective field theory with hadronic-like spectral functions in the QGP until temperatures as high as (3)(4)T c (Biró -Jakovác, with brown [133]). In this latter approach the thermodynamic quantities can be calculated analytically.…”

“…The scaled pressure, P/T 4 and energy density, ε/T 4 of identified hadrons in pp, pA and AA collisions at various collision energies, in the function of the temperature T . The theoretical curves are taken from[129][130][131][132][133]. , EV, r = 0.15 fm Kovacs-Szep-Wolf (Polyakov loop) Biro-Jakovac (hadronic dof) Tsallis-thermometer…”