Measuring WWZ and WWgamma coupling constants with Z-pole data

TL;DR

This paper uses Z-pole data to precisely measure the WWZ and WWgamma coupling constants through their effects on radiative corrections, providing indirect measurements that surpass some direct methods in accuracy.

Contribution

It introduces a method to determine gauge boson couplings from electroweak observables near the Z-pole, improving precision over direct measurements.

Findings

Standard model predictions agree with measurements

Indirect coupling measurements are more precise than some direct ones

Determined epsilon parameters and couplings from Z-pole data

Abstract

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.