UA1 and UA2 collider observations of W and Z bosons

What changed

In 1983, two collaborations at CERN’s proton–antiproton collider reported evidence for the charged W and neutral Z bosons. UA1 and UA2 separately observed high-energy electrons with missing energy consistent with W decay. Later that year, UA1 reported electron and muon pairs near the expected Z mass and UA2 reported electron-pair events consistent with Z decay. The measurements supplied direct evidence for particles predicted by electroweak theory.

Scientific scope

In 1983, two collaborations at CERN’s proton–antiproton collider reported evidence for the charged W and neutral Z bosons. UA1 and UA2 separately observed high-energy electrons with missing energy consistent with W decay. Later that year, UA1 reported electron and muon pairs near the expected Z mass and UA2 reported electron-pair events consistent with Z decay. The measurements supplied direct evidence for particles predicted by electroweak theory. These are separate searches using two detectors at the same collider, not four different particles. The original samples were small, and their event selections and uncertainties differ. Later enlarged samples should not be substituted for the initial 1983 observations. The team-level attributions do not provide a complete list of individual authors.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. These are separate searches using two detectors at the same collider, not four different particles. The original samples were small, and their event selections and uncertainties differ. Later enlarged samples should not be substituted for the initial 1983 observations. The team-level attributions do not provide a complete list of individual authors.

Contributors

• The named authors in the research record · SCIENCE: Credit belongs to the cited collaborations. The individual author list is incomplete; no sole discoverer or individual effort share is inferred.

• Experimental Observation of the Intermediate Vector Bosons W+, W− and Z0
• UA1: isolated high-energy electrons with missing energy
• UA2: isolated electrons and missing transverse energy
• UA1: lepton pairs of invariant mass near 95 GeV
• UA2: evidence for Z⁰ decays to electron pairs

Provisional WRS assessment, edition 2026-10-28.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

Full scientific record · Browse contribution grades · Request a correction