= From renormalizability to electroweak predictions
The 1999 recognition of <Gerard 't Hooft> and <Martinus J. G. Veltman> concerned the theoretical quantum structure of the <electroweak interaction>.<Gerard 't Hooft homepage by Gerardus 't Hooft>[Nobel Prize paragraph]{ref} <Renormalizability> makes repeated <radiative corrections> predictive from a fixed set of inputs. It does not imply that the <perturbation series> converges, nor that <renormalization> alone chooses the correct <particle> content or excludes all physics beyond the <Standard Model>.
The <Gargamelle> collaboration prepared an experimental test by exposing its heavy-liquid <bubble chamber> to <neutrino> and <antineutrino> beams at CERN. The readout selected events producing <hadrons> without an identified <muon> or <Electron>, compared with events containing a charged <lepton>. Its 1974 report assessed alternative origins from <neutrons> and long-lived neutral <kaons>, finding them insufficient to explain the sample. That supported <neutral currents>; it did not isolate a <radiative correction> or demonstrate <renormalizability>.<Observation of neutrino-like interactions without muon or electron in the Gargamelle neutrino experiment (1974) by F. J. Hasert>[Abstract, Nuclear Physics B 73 (1974), pp. 1–22]{ref}
The distinction matters when using the <tree-level electroweak gauge-boson masses>:
$$
m_W=m_Z\cos\theta_W.
$$
Beyond tree level, <self-energies>, <interaction vertices> and <counterterms> alter how chosen input <observables> predict another <observable>. The <Weinberg angle> then needs a specified <renormalization scheme>; inserting its value from one convention into a formula from another can create an apparent discrepancy. A meaningful higher-order test must state both its independent experimental inputs and the calculated <loop order>.
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