The Monte Carlo program KORALZ, version 3.8, for the lepton or quark pair production at LEP/SLC energies

A Monte Carlo program for τ pair production and decay applicable to the experiments in e+e− colliders in the Z resonance energy range is presented. The program includes initial and final state bremsstrahlung corrections up to the O(α2) (with exclusive exponentiation), and O(α) electroweak corrections. More than twenty distinct τ decay modes can be generated: (a) leptonic modes τ−→vve−(γ) and vvμ-(γ); (b) one-meson modes, vπ− and vK−; (c) two-me son modes, ν{π− π0}ρ−, ν{K− π0}K∗− and ν{K0π−}K∗−; (d) three-meson modes, ν {π− 2π0}a−1, ν{2π− π+}a−1, νK+ K− π−, νK0K0π−, νK−K0π0, νK−π0π0, νK−π−π+, νK0π0π- and νηπ−π0; (e) four-pion modes, νπ−3π0, and ν2π−π+π0 (including the ωπ− contribution); (f) multi-pion modes, νnπ±,0 with n>4; and finally the decay τ-→νπ-π0γ from the ω→πγ. Complete O(α) QED corrections are included in the leptonic decay channels, and for other decay channels an interface is provided to the PHOTOS Monte Carlo generator for approximate simulation of the QED corrections. The program includes three libraries of pure electroweak corrections from three independent groups of authors. The program can also be used for the generation of final states different from τ+τ- pairs, i.e., it is able to generate μ+μ-, νḡn, and under some restrictions uū, dd, cc, ss and bb final states.