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Manuscript Title: A Monte Carlo program for generating hadronic final states in electron-positron annihilations.
Authors: L. Angelini, L. Nitti, M. Pellicoro, G. Preparata, G. Valenti
Program title: EPOS
Catalogue identifier: ACDM_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 34(1985)371
Programming language: Fortran.
Computer: CDC 7600.
Operating system: 7000 SCOPE 2.1.4 (CDC)/NOS-BE LEVEL 587, VAX-VMS.
RAM: 240K words
Word size: 32
Keywords: Particle physics, Elementary, Monte carlo, E+e- annihilation, Hadron production, Phase space.
Classification: 11.2.

Nature of problem:
High energy electron-positron annihilations, at present investigated at PETRA and PEP and in the near future at SLC and LEP, have shown the production of a large number of particles in the final state (30 or 40 particles are not uncommon at W = 35 GeV). The complexity of this phenomenon needs a theoretical frame-work for describing and understanding the basic physical mechanism involved. The present program is an event generator of hadronic final states based on the Fire-String theory and has been shown to reproduce very well all the features experimentally observed.

Solution method:
The program is based on the Monte Carlo method and it generates events with weight = 1 using the Fire-String theory. The notion of Fire-String comes from the description of hadronic matter in terms of bound states (bags) of quarks and antiquarks in the theoretical framework named Quark-Geometro-Dynamics. In this approach to the dynamics of high energy physics one can define a highly excited quark-antiquark bound state with a cylindrical structure, called Fire-String (FS). The evolution of the FS and its decay modes are responsible for the deposition of hadrons in the final states. All these physical ideas have been implemented in the present program.

The program describes quite well all the features of hadronic final states for energy ranging from 5 GeV to 36 GeV, furthermore its yield can be extrapolated to SLC and LEP energies. A maximum production of 400 particles in the final state is allowed. It can however be easily modified to allow any number of particles.