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Manuscript Title: The Monte Carlo program KORALZ, version 4.0, for lepton or quark pair production at LEP/SLC energies.
Authors: S. Jadach, B.F.L. Ward, Z. Was
Program title: KORALZ, VERSION 4.0
Catalogue identifier: ACBK_v2_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 79(1994)503
Programming language: Fortran.
Computer: HP-9000/715.
Operating system: UNIX, VM/CMS.
RAM: 1000K words
Word size: 32
Keywords: Particle physics, Elementary, Event simulation, Radiative corrections, Heavy lepton tau, Monte carlo simulation, Electrodynamics quantum, Spin polarization, Electro-weak theory.
Classification: 11.2.

Nature of problem:
Spin polarization of the tau in the process e+e- -> tau+tau-(etagamma), tau+- -> X+- is used as an important data point for precise tests of the standard electroweak theory. The effects due to QED bremsstrahlung and apparatus efficiency have to be subtracted from the data. The program may also be applied for the production of u, d, s, c, b quarks and neutrinos after appropriate redefinition of the coupling constants and massess. It may be used, as well, to simulate the muon pair production process. The precision of the program in the case of quarks is restricted.

Solution method:
The Monte Carlo simulation of the combined tau production and decay process is used to calculate the spin effects and effects of radiative corrections, including hard bremsstrahlung, simultaneously. Any experimental cut and apparatus efficiency may be introduced easily by rejecting some of the generated events.

The incoming e+- and outgoing tau+- may have only longitudinal polarizations. The total centre of mass energy is restricted to the range from about 20 GeV to 150 GeV. High precision of the program is assured only in the region of the Z where interference of bremsstrahlung from initial and final states can be neglected. When the program is used for the simulation of quark production, no hadronization, as well as no exclusive QCD corrections, are included.

Running time:
Efficiency is 40 CPU sec. of HP-9000/715 per 1000 events, for the parameter setting as in the demonstration output.