This is a code to compute a scaled variance of number of particles in an ensemble with conservation laws. A particular application is meant for heavy ion collisions. The setting is the following:
- In a box of volume V there is a gas (optionally classical Boltzmann, or quantum Bose/Fermi) at temperature T, baryon chemical potential muB, strangeness chemical potential muS, and charge chemical potential muQ.
- The gas consists of many particle species
- Custom conservation laws can be imposed on the ensemble: energy / baryon number / strangeness / electric charge conservation
- The task is to compute fluctuations of a specific subset of particle species in this ensemble.
The problem is very hard in general, but solved in the limit of large volume in a paper by Hauer, Begun, and Gorenstein. This code implements the formulas from the paper in case of Maxwell-Boltzmann gas and in case of quantum gas too.
- Eigen3 library (eigen.tuxfamily.org)
- GNU Scientific Library (GSL) >= 1.15
- SMASH library (smash-transport.github.io), which requires the first two anyway.
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Set the SMASH_DIR environment variable by executing
export SMASH_DIR=[...]/smash
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Copy the cmake files to find the libraries for the project
cp -r $SMASH_DIR/cmake .. -
Run cmake and make
mkdir build && cd build cmake .. make -
If Pythia is not found, try
cmake .. -DPythia_CONFIG_EXECUTABLE=[...]/pythia8235/bin/pythia8-config