Upper Limits on Electric and Weak Dipole Moments of W-Boson

TL;DR

This paper sets upper limits on the electric and weak dipole moments of the W-boson by analyzing LEP-II data, providing constraints on CP-violating gauge couplings and discussing implications for W-boson EDM.

Contribution

It introduces new upper limits on W-boson CP-violating couplings and EDM, based on LEP-II measurements, improving constraints over previous analyses.

Findings

Upper limits | ilde{\kappa}_Z|<0.13 and | ilde{\lambda}_Z|<0.31 at 95% CL

Constraints on W-boson EDM from electron and neutron EDM measurements

Results are comparable with previous decay product analyses

Abstract

The total cross-sections of the reaction e+e- --> W+W-, as measured at LEP-II at centre-of-mass energies between 183 and 207 GeV are used to derive the upper limits on the parameters of CP-violating (P-odd and C-even) triple gauge-boson couplings WW\gamma and WWZ. The 95% CL limits |\widetilde{\kappa}_Z|<0.13 and |\widetilde{\lambda}_Z|<0.31 are obtained assuming local SU(2)_L x U(1)_Y gauge invariance. Our results are comparable with the previous ones obtained through the analysis of the W decay products. We also discuss the upper limits on the electric dipole moment (EDM) of the W-boson, which follow from the precision measurements of the electron and neutron EDM.