Hadron Resonance Gas (HRG) Module
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The **HRG** (Hadron Resonance Gas) module of the NSF-funded `MUSES <https://musesframework.io/>`_ project provides methods for calculating the equation of state (EoS) of strongly interacting hadronic matter at zero and finite temperature :math:`T`, baryon chemical potential :math:`\mu_B`, strangeness chemical potential :math:`\mu_S`, and  charge chemical potential :math:`\mu_Q`. It can be used to compute the EoS of an ideal hadron resonance gas (IHRG) as well as a quantum van der Waals (QvdW) HRG, which includes mean-field interactions between hadrons.

The module relies on the **Thermal-FIST** package (Thermal, Fast and Interactive Statistical Toolkit) version 1.6, with its C++ source code (GPLv3) `available on GitHub <https://github.com/vlvovch/Thermal-FIST>`_.

It can be used to compute the HRG EoS over the range:
   - **Temperature:** :math:`0 < T < 300` MeV
   - **Chemical potentials:** Accessible range of chemical potentials, :math:`\mu = \sqrt{\mu_B^2 + \mu_Q^2 + \mu_S^2}`, typically extending from 0 to 1000 MeV. Calculations should be performed only outside the condensation region, defined by the conditions: :math:`\mu_Q < m_\pi`, :math:`\mu_S < m_{K^0}`, and :math:`(\mu_S + \mu_Q) < m_{K^\pm}`; however, the use of interacting pions through an effective mass model allows for calculations in the pion condensation region, currently restricted to :math:`\mu_Q < 2 \times m_\pi`.

.. | **When using results from this module for scientific publication, please cite:**
.. | V. Vovchenko and H. Stoecker, *Comput. Phys. Commun. 244, 295–310* (2019), `arXiv:1901.05249 <https://arxiv.org/abs/1901.05249>`__ [nucl-th].

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| **Original module source code was developed by:** Johannes Jahan\ :math:`^{1}`,
 Feyisola Nana\ :math:`^{2}` &
 Volodymyr Vovchenko\ :math:`^{1}`.

| :math:`^{1}` *Department of Physics, University of Houston, Houston, TX 77204, USA.* 
| :math:`^{2}` *Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.*

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.. toctree::
   :maxdepth: 1
   :caption: Contents
   :glob:

   _contents/physics.rst
   _contents/quickstart.rst
   _contents/units.rst
   _contents/parameters.rst
   _contents/code_structure.rst
   _contents/troubleshooting.rst