A brief introduction to PYTHIA 8.1

This program has been imported from the CPC Program Library held at Queen's University Belfast (1969-2018) Abstract The Pythia program is a standard tool for the generation of high-energy collisions, comprising a coherent set of physics models for the evolution from a few-body hard process to a complex multihadronic final state. It contains a library of hard processes and models for initial- and final-state parton showers, multiple parton-parton interactions, beam remnants, string fragmentation and particle decays. It also has a set of utilities and interfaces to external programs. While previous versions ... Title of program: Pythia 8.1 Catalogue Id: ACTU_v3_0 Nature of problem high-energy collisions between elementary particles normally give rise to complex final states, with large multiplicities of hadrons, leptons, photons and neutrinos. The relation between these final states and the underlying physics description is not a simple one, for two main reasons. Firstly, we do not even in principle have a complete understanding of the physics. Secondly, any analytical approach is made intractable by the large multiplicities. Versions of this program held in the CPC repository in Mendeley Data ACTU_v1_0; PYTHIA 5.7 AND JETSET 7.4; 10.1016/0010-4655(94)90132-5 ACTU_v2_0; PYTHIA V6.154; 10.1016/S0010-4655(00)00236-8 ACTU_v2_1; PYTHIA Version number: 6.420; 10.1016/j.cpc.2009.08.008 ACTU_v3_0; Pythia 8.1; 10.1016/j.cpc.2008.01.036 ACTU_v4_0; Pythia 8.2; 10.1016/j.cpc.2015.01.02