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Manuscript Title: A program for e+e- -> 4f, 4fγ with nonzero fermion masses.
Authors: K. Kolodziej, F. Jegerlehner
Program title: ee4fγ
Catalogue identifier: ADTQ
Journal reference: Comput. Phys. Commun. 159(2004)106
Programming language: Fortran 90.
Computer: All.
Operating system: Unix/Linux.
RAM: 4M words
Word size: 32
Keywords: e+ e- annihilation, SM, Lowest order four fermion reactions, Bremsstrahlung, nonzero fermion masses, Particle physics, Elementary, Computing, Event simulation, Quantum electrodynamics.
Classification: 11.1, 11.2, 11.4.

Subprograms used:
Cat Id Title Reference
ACPR RANLUX CPC 79(1994)111

Nature of problem:
Description of all e+e- -> 4 fermions and corresponding bremsstrahlung reactions that are possible in the Standard Model (SM) to lowest order and with nonzero fermion masses at center of mass energies typical for next generation linear colliders. Such reactions are relevant, typically, for W-pair or intermediate mass Higgs boson production and decay.

Solution method:
Matrix elements are calculated with the helicity amplitude method. The phase space integration is performed numerically utilizing a multi-channel Monte Carlo method.

No higher order effects are taken into account, except for assuming the fine structure constant and the strong coupling at the appropriate scale and partial summation of those one particle irreducible loop corrections which are inducing the (fixed) finite widths of unstable particles.

Running time:
The running time depends strongly on a selected channel and desired precision of the result. The results of the appended test run have been obtained on a 800 MHz Pentium III processor with the use of Absoft Fortran 90 compiler in about 9 minutes. In order to obtain a precision level below one per mille a few million calls to the integrand are required. This results in less than one hour running time for the fastest channel e+e- -> vuvu vrvr and more than 100 hours running time for the slowest channel e+e- -> e+e- e+e-. However, the typical running time for channels that are relevant for the W-pair or Higgs boson production is several hours.