The 1999 recognition of Gerard 't Hooft and Martinus J. G. Veltman concerned the theoretical quantum structure of the electroweak interaction.[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.[ref]
The distinction matters when using the tree-level electroweak gauge-boson masses: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.