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Manuscript Title: Monte Carlo simulation of the process e+e- -> tau+tau-, tau+- -> X+- including radiative O(alpha**3) QED corrections, mass and spin effects.
Authors: S. Jadach, Z. Was
Program title: KORAL-B
Catalogue identifier: AABH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 36(1985)191
Programming language: Fortran.
Computer: IBM 4341.
Operating system: VM/SP R2.
RAM: 45K words
Word size: 32
Keywords: Particle physics, Elementary, Corrections radiative, Heavy lepton tau, Monte carlo simulation, Spin polarization, Electroweak effects, Phase space.
Classification: 11.2.

Nature of problem:
In the process e+e- -> tau+tau-(gamma), tau+- -> X+- the effects due photon radiation, spin polarization and finite mass of the tau lepton are of similar magnitude. They should be taken into account in the analysis of the experimental data in order to subtract the trivial phenomena from the interesting ones like electroweak effects or lepton universality.

Solution method:
The Monte Carlo simulation of the combined tau production and decay process is used to analyse 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 part of the generated events. A new method of calculating QED distributions numerically is developed.

Incoming e+- and outgoing tau+- may have arbitrary (transverse and longitudinal) polarizations. The total centre of mass energy is restricted to the range from the tau production threshold to about 45 GeV. At higher energies the contribution from the Z0 exchange should be treated in a more complete way. Only one prong decays of tau are included. The program can simulate the production of heavy quarks b and c (without fragmentation) in the same energy range.

Running time:
Efficiency for polarized e+- is 120 events per CPU sec. For polarized e+- the efficiency depends on the longitudinal components of the e+- polarizations. For transverse polarized e+- it is 13 events per CPU sec.