The Monte Carlo program KORALZ, for the lepton or quark pair production at LEP/SLC energies - from version 4.0 to version 4.04. S. Jadach, B.F.L. Ward, Z. Was.

Title of program: KORALZ, version 4.04
Catalogue identifier: ADKX
Ref. in CPC: 124(2000)233
Distribution format: tar gzip file
Operating system: UNIX, HP-UX 10.2
High speed store required: 1MK words
Number of bits in a word: 32
Number of lines in distributed program, including test data, etc: 215118
Programming language used: Fortran

CPC Program Library subprograms used:

 Cat. Id.  Title                             Ref. in CPC
 ADKY      GenLib, version 2.0                124(2000)238                   
 ADKZ      TTGlib, version 2.0                124(2000)243                   

Other versions of this program:

 Cat. Id.  Title                             Ref. in CPC
 ACBK      KORALZ, version 3.8                66(1992)276                    
 ACTI      KORALZ, version 4.0                79(1994)503                    

Nature of physical 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 be applied also to the production of u, d, s, c, b quarks and neutrinos after appropriate redefinition of the coupling constants and masses. It may be used, as well, to simulate the muon pair production process. The precision of the program in the case of quarks and electron neutrino is restricted. Certain classes of anomalous couplings can be included for tau, q and nu final states.

Method of solution
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 easily be introduced by rejecting some of the generated events.

Restrictions on the complexity of the problem
The incoming e+- and outgoing tau+- may have only longitudinal polarizations. The total centre-of-mass energy is restricted to 240 GeV. The 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.

Unusual features of the program
The distribution file includes the code for the programs GengLib, version 2.0 (Comput. Phys. Commun. 124(2000)248 and TTGlib, version 2.0 (Comput. Phys. Commun. 124(2000)243).