Hadronization (or hadronisation) 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[1] and colour string decay into hadrons.[2] The transformation of quark-gluon plasma into hadrons is studied in lattice QCD numerical simulations, which are explored in relativistic heavy-ion experiments.[3] Quark-gluon plasma hadronization occurred shortly after the Big Bang when the quark–gluon plasma cooled down to the Hagedorn temperature (about 150 MeV) when free quarks and gluons cannot exist.[4] In string breaking new hadrons are forming out of quarks, antiquarks and sometimes gluons, spontaneously created from the vacuum.[5]
^Müller, Berndt (2016), Rafelski, Johann (ed.), "A New Phase of Matter: Quark-Gluon Plasma Beyond the Hagedorn Critical Temperature", Melting Hadrons, Boiling Quarks - From Hagedorn Temperature to Ultra-Relativistic Heavy-Ion Collisions at CERN, Cham: Springer International Publishing, pp. 107–116, arXiv:1501.06077, Bibcode:2016mhbq.book..107M, doi:10.1007/978-3-319-17545-4_14, ISBN978-3-319-17544-7