ABSTRACT
The experimental discovery of weak bosons at the CERN p p ¯ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429494062/4af1a3a3-6c2d-45d0-b33d-a81d6d438301/content/eq1535.tif"/> collider gave spectacular support to the standard electroweak gauge theory that had predicted them. These bosons are detected by their decays. In the standard model W and Z decay through their fundamental gauge couplings to the basic quarks and leptons. The first detected W decays were the leptonic modes W → e ν https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429494062/4af1a3a3-6c2d-45d0-b33d-a81d6d438301/content/eq1536.tif"/> . The amplitude for W − → e − + ν ¯ e https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429494062/4af1a3a3-6c2d-45d0-b33d-a81d6d438301/content/eq1537.tif"/> decay is M = − i g 2 ϵ a λ ( P ) u ¯ ( l ) γ a 1 2 ( 1 − γ 5 ) v ( k ) , https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429494062/4af1a3a3-6c2d-45d0-b33d-a81d6d438301/content/eq1538.tif"/>
