Martin W. Gruenewald | Searcharxiv

arXiv2000

Four-Fermion Production in Electron-Positron Collisions

This report summarises the results of the four-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the calculation of four-fermion processes in electron-positron collisions at LEP-2 centre-of-mass energies are presented, concentrating on predictions for four main reactions: W-pair production, visible photons in four-fermion events, single-W production and Z-pair production. Based on a comparison of results derived within different approaches, theoretical uncertainties on these predictions are established.

hep-ph↗

arXiv1999

Measuring WWZ and WWgamma coupling constants with Z-pole data

Triple gauge boson couplings between Z, gamma and the W boson are determined by exploiting their impact on radiative corrections to fermion-pair production in e+e- interactions at centre-of-mass energies near the Z-pole. Recent values of observables in the electroweak part of the Standard model are used to determine the four parameters epsilon_1, epsilon_2, epsilon_3 and epsilon_b. In a second step the results on the four epsilon parameters are used to determine the couplings Delta-g^1_Z and Delta-kappa_gamma. For a wide range of scales, these indirect coupling measurements are more precise than recent direct measurements at LEP 2 and at the TEVATRON. The Standard model predictions agree well with these measurements.

hep-ph↗