order of the Z boson mass (91 GeV) or higher, the virtual Z boson exchange has an effect of a tiny correction () to the amplitude of the electromagnetic process. Particle accelerators with energies necessary to observe neutral current interactions and to measure the mass of Z boson weren't available until 1983. On the other hand, Z boson interactions involving neutrinos have distinctive signatures: They provide the only known mechanism for elastic scattering of neutrinos in matter; neutrinos are almost as likely to scatter elastically (via Z boson exchange) as inelastically (via W boson exchange), of major experimental significance, in, e.g. , the Sudbury Neutrino Observatory experiment. Weak neutral currents were predicted by electroweak theory developed mainly by Abdus Salam, John Clive Ward, Sheldon Glashow and Steven Weinberg, and confirmed shortly thereafter in 1973, in a neutrino experiment in the Gargamelle bubble chamber at CERN. See also Charged current Electric current Flavor changing neutral current Quantum chromodynamics Sudbury Neutrino Observatory#Neutral current interaction Weak charge References External links Electroweak theory