This code is based on the work of Constantin Loizides and Andreas Morsch, as detailed in Phys.Lett. B773 (2017) 408-411 (arXiv:1705.08856).  It was first ported to run on top of a default PYTHIA installation by Austin Baty ([email protected]).  

This implementation is designed to run on top of an already installed version of PYTHIA.  We suggest first installing the latest PYTHIA 8.3 version (http://home.thep.lu.se/Pythia/, 8.135 at the point of writing this readme) and confirming that the generator runs before trying to run this code.  Additionally, an installation of ROOT is also required.  The PYTHIA8 static library and the dynamic ROOT libraries will be used when compiling the HG-PYTHIA code.  g++ and make are used to build the code and need to be installed on the system you are building the code with.

Once you have a working version of PYTHIA, go to the directory where you like to install HG-PYTHIA.Get the code with:
git clone https://github.com/abaty/HGPythia.git HG-PYTHIA

Inside the HG-PYTHIA directory, check the Makefile and adjust the path to the PYTHIA libary.

Then, type 
make

This should create a directory called 'bin' with an executable if everything runs correctly.  You can execute the code by running:

./bin/HGPYTHIA.exe <nEvents> <outputName> <energy> <A1> <A2> <maxb>

where the number of events, the name of the root file, the collision energy, nucleus 1 and 2 mass numbers, max impact parameter.

Collision energies at RHIC and LHC are supported.
The size of nuclei are 1,3,6,16,20,40,129,197,208.
The max impact parameter will also be determined based on the size of the given nuclei.

If you like to give a specific seed to the random generator, use
export RNGoffset=12345

Some settings in the main() function might need to be changed if you would like to run a collision system/energy that is not yet supported. If you make changes to the source code, you can recompile with the command:

make clean
make

Many questions about the code can just be figured out by reading the core part of the event generation, which is only around 200 lines long (l371 to l551).
If you have questions or comments please contact C.Loizides and/or A.Baty.