PYTHIA is a computer simulation program for predicting events at very high energies in particle accelerators. [1]
PYTHIA was originally written in FORTRAN 77, until the 2007 release of PYTHIA 8.1 which was rewritten in C++. [1] Both the Fortran and C++ versions were maintained until 2012 because not all components had been merged into the 8.1 version. [1] However, the latest version already includes new features not available in the Fortran release. [2] PYTHIA is developed and maintained by an international collaboration of physicists, consisting of Christian Bierlich, Nishita Desai, Leif Gellersen, Ilkka Helenius, Philip Ilten, Leif Lönnblad, Stephen Mrenna, Stefan Prestel, Christian Preuss, Torbjörn Sjöstrand, Peter Skands, Marius Utheim and Rob Verheyen. [3]
The following is a list of some of the features PYTHIA is capable of simulating: [1]
A gluon is a type of massless elementary particle that mediates the strong interaction between quarks, acting as the exchange particle for the interaction. Gluons are massless vector bosons, thereby having a spin of 1. Through the strong interaction, gluons bind quarks into groups according to quantum chromodynamics (QCD), forming hadrons such as protons and neutrons.
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Hadronization is the process of the formation of hadrons out of quarks and gluons. There are two main branches of hadronization: quark-gluon plasma (QGP) transformation and colour string decay into hadrons. The transformation of quark-gluon plasma into hadrons is studied in lattice QCD numerical simulations, which are explored in relativistic heavy-ion experiments. Quark-gluon plasma hadronization occurred shortly after the Big Bang when the quark–gluon plasma cooled down to the Hagedorn temperature when free quarks and gluons cannot exist. In string breaking new hadrons are forming out of quarks, antiquarks and sometimes gluons, spontaneously created from the vacuum.
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