= W and Z discovery experiments
{c}
A <W boson> decay can leave one visible <charged lepton> and a large <missing transverse momentum>; a <Z boson> decay can instead supply two visible <leptons> whose <four-momenta> determine an <invariant mass>. The two signatures answer the same existence question with different missing information. The <electroweak unification history> recognized by the 1979 <Nobel Prize in Physics> predates these 1983 observations: the <W boson> and <Z boson> were predictions to test, rather than particles first proposed in 1983.
The <Super Proton-Antiproton Synchrotron> stored counterrotating <proton> and <antiproton> beams; <stochastic cooling> made accumulation of the scarce <antiprotons> practical. <Carlo Rubbia>'s 1984 lecture describes <track reconstruction> in a large <drift chamber> inside a <magnetic field>, surrounded by segmented <particle calorimeters>. Their nearly complete angular coverage allowed an imbalance test for unobserved <neutrinos>.<Experimental Observation of the Intermediate Vector Bosons W+, W− and Z0 by Carlo Rubbia>[1984 lecture, section 3, p.247, Fig.5; section 4, Figs.7–8]{ref}
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