Measurement of gauge boson couplings and W spin density matrix

TL;DR

This paper reports measurements of W boson gauge couplings and spin density matrices at LEP2, confirming Standard Model predictions and setting limits on possible new physics in gauge interactions.

Contribution

It provides the first comprehensive measurement of W boson couplings to neutral gauge bosons and CP-violating effects using spin density matrix analysis.

Findings

W boson couplings agree with Standard Model

Limits set on CP-violating couplings

No evidence for three neutral gauge boson couplings

Abstract

During the LEP2 period the e+e- collider increased its center of mass energy from 161 GeV to 209 GeV and a total integrated luminosity of approximately 700 pb-1 was recorded per experiment. Pairs of W bosons are produced and allow the study of gauge boson couplings involving W, Z and photon. The coupling of the W boson to the neutral gauge bosons have been measured and are in agreement with the Standard Model prediction. Limits are set on CP-violating couplings by a Spin Density Matrix analysis of the W decay products. No evidence has been found for couplings of three neutral gauge bosons. Limits are derived on couplings of four gauge bosons.