Physics of W bosons at LEP

TL;DR

This paper reviews the extensive experimental results from LEP on W-boson production, properties, and couplings, providing critical tests of the Standard Model and insights into electroweak symmetry breaking.

Contribution

It summarizes the key measurements and discoveries related to W bosons at LEP, including cross sections, gauge couplings, helicity states, and mass determination, highlighting their significance for the Standard Model.

Findings

Measured W-boson production cross sections and couplings.

Observed the longitudinal helicity component of W bosons.

Precisely determined the W-boson mass and its implications.

Abstract

The high-energy and high-luminosity data-taking campaigns of the LEP e^+e^- collider provided the four collaborations, ALEPH, DELPHI, L3 and OPAL, with about 50000 W-boson pairs and about a thousand singly-produced W bosons. This unique data sample has an unprecedented reach in probing some aspects of the Standard Model of the electroweak interactions, and this article reviews several achievements in the understanding of W-boson physics at LEP. The measurements of the cross sections for W-boson production are discussed, together with their implication on the existence of the coupling between Z and W bosons. The precision measurements of the magnitude of triple gauge-boson couplings are presented. The observation of the longitudinal helicity component of the W-boson spin, related to the mechanism of electroweak symmetry breaking, is described together with the techniques used to probe the CP and CPT symmetries in the W-boson system. A discussion on the intricacies of the measurement of the mass of the W boson, whose knowledge is indispensable to test the internal consistency of the Standard Model and estimate the mass of the Higgs boson, concludes this review.