ZFITTER: a semi-analytical program for fermion pair production in [formula omitted] annihilation, from version 6.21 to version 6.42

Abstract

ZFITTER is a Fortran program for the calculation of fermion pair production and radiative corrections at high energy e + e − colliders; it is also suitable for other applications where electroweak radiative corrections appear. ZFITTER is based on a semi-analytical approach to the calculation of radiative corrections in the Standard Model. We present a summary of new features of the ZFITTER program version 6.42 compared to version 6.21. The most important additions are: (i) some higher-order QED corrections to fermion pair production, (ii) electroweak one-loop corrections to atomic parity violation, (iii) electroweak one-loop corrections to ν ¯ e ν e production, (iv) electroweak two-loop corrections to the W boson mass and the effective weak mixing angle. Program summary Title of program: ZFITTER version 6.42 (18 May 2005) Catalogue identifier:ADMJ_v2_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADMJ_v2_0 Authors of original program: D. Bardin, P. Christova, M. Jack, L. Kalinovskaya, A. Olshevski, S. Riemann, T. Riemann Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Reference for ZFITTER version 6.21: D. Bardin et al., Comput. Phys. Comm. 133 (2001) 229–395 Operating system: UNIX/LINUX, program tested under, e.g., HP-UX and PC/Linux Programming language used: FORTRAN 77 High speed storage required: <2 MB No. of lines in distributed program, including test data, etc.:29 164 No. of bytes in distributed program, including test data, etc.:185 824 Distribution format:tar.gz Does the new version supersede the previous version:Yes Nature of the physical problem: Fermion pair production is an important reaction for precision tests of the Standard Model, at LEP/SLC and future linear colliders at higher energies. For this purpose, QED, electroweak and QCD radiative corrections have to be calculated with high precision, including higher order effects. Multi parameter fits used to extract model parameters from experimental measurements require a program of sufficient flexibility and high calculational speed. ZFITTER combines these two aspects by employing analytical integrations of matrix elements and at most one-dimensional numerical integration, as well as a variety of flags defining the physics content used. The calculated predictions are typically at the per mille precision level, sometimes better. Method of solution: Numerical integration of analytical formulae. Reasons for new version:Addition of substantial material into the code: covering of more reactions; more accurate description of existing reactions. Summary of revisions:New parts for predicting atomic parity violation and for neutrino pair production; more accurate higher order QED corrections for fermion pair production; two-loop corrections to the predictions of W mass and of the weak mixing angle. Restrictions on the complexity of the problem: Fermion pair production is described below the top quark pair production threshold. Photonic corrections are taken into account with simple cuts on photon energy, or the energies and acollinearity of the two fermions, and one fermion production angle. The treatment of Bhabha scattering is less advanced. Typical running time: On a Pentium IV PC installation (2.8 GHz) using g77 under Linux 2.4.21, approximately 23 s are needed to run the standard test of subroutine ZFTEST. This result is for a default/recommended setting of the input parameters, with all corrections in the Standard Model switched on. ZFTEST computes 12 cross-sections and cross-section asymmetries for 8 energies with 5 interfaces, i.e. about 360 cross-sections in 23 s.