arXiv subjects

A. Olchevski

Publications and source records attributed to A. Olchevski.

6 recordsLinked to original sources

arXiv2000

Two-Fermion Production in Electron-Positron Collisions

This report summarizes the results of the two-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the theoretical calculations of the two fermion production process in the electron-positron collision at LEP2 center of the mass energies are reported. The Bhabha process and the production of muon, tau, neutrino and quark pairs is covered. On the basis of comparison of various calculations, theoretical uncertainties are estimated and compared with those needed for the final LEP2 data analysis. The subjects for the further studies are identified.

hep-ph↗

arXiv2000

ZFITTER v.6.21 - A Semi-Analytical Program for Fermion Pair Production in e+e- Annihilation

We describe ZFITTER, a Fortran program based on a semi-analytical approach to fermion pair production in e+e- annihilation at a wide range of centre-of-mass energies, including the PETRA, TRISTAN, LEP1/SLC, and LEP2 energies. A flexible treatment of complete O(alpha) QED corrections and of some higher order contributions is made possible with three calculational chains containing different realistic sets of restrictions in the photon phase space. Numerical integrations are at most one-dimensional. Complete O(alpha) weak loop corrections supplemented by selected higher-order terms may be included. The program calculates Delta r, the Z width, differential cross-sections, total cross-sections, integrated forward-backward asymmetries, left-right asymmetries, and for tau pair production also final-state polarization effects. Various interfaces allow fits to be performed with different sets of free parameters.

hep-ph↗

arXiv1997

Event Generators for WW Physics

The report summarizes the results of the activities of the Working Group on Event Generators for WW Physics at CERN during 1995.

hep-ph↗

arXiv1996

GENTLE/4fan v.2.0 - A Program for the Semi-Analytic Calculation of Predictions for the Process e+e- -> 4f

We describe version 2.0 of the Fortran program GENTLE/4fan for the semi-analytic computation of cross-sections and distributions in four-fermion production in e+e- annihilation. GENTLE/4fan covers all charged current and neutral current our-fermion final states with no identical particles, no electrons, and no electron neutrinos in the final state. Initial state radiation representing the most relevant quantum corrections and anomalous triple gauge boson couplings have been included.

hep-ph↗

arXiv1995

Off-shell $W$-pair production in $e^+ e^-$-annihilation. Initial state radiation

With a current-splitting technique, we calculate the gauge-invariant initial-state radiation to order \oalf\ with soft-photon exponentiation for on- and off-shell $W$-pair production. This result generalizes the convolution formula, which is known from the description of the $Z$ resonance, to the case of the production of two $W$-bosons. After up to eightfold analytical integrations, a sufficiently smooth integral over three invariant masses remains to be treated numerically. Including the Coulomb singularity, the largest corrections are covered. We discuss the corrections in a large energy range up to $\sqrt{s}$=1~TeV and draw numerical conclusions on their influence on the $W$-mass determination at LEP~200. Table~1 and figure~5 are revised after correcting the analytical formulae for the nonuniversal corrections.

hep-ph↗

arXiv1994

Semi-Analytical Approach to Four-Fermion Production in $e^+ e^-$ Annihilation

A study of the semi-analytical approach to four-fermion production in $e^+ e^-$ annihilation is presented. We classify all possible four-fermion final states and present results of new calculations for the `basic' processes with the $WW,ZZ$, and $ZH$ off-shell production together with some examples of `background' processes. The Initial State Radiative corrections are included for the basic processes. Several numerical examples are given in the energy range from LEP2 up to $\sqrt{s}=1$ TeV.

hep-ph↗