SEEKING SIGNS OF A 2ND-Z

Principles of minimality and unifiability lead us to a unique family of mutants of the electroweak theory which are parametrized solely by the mass of a heavy Z boson. These models generate an additional vectorial current-current interaction at low energy, and modify the properties of the observed Z boson in a way that would appear (in the context of the standard model) as an apparently fractional number (exceeding three) of light neutrino species. Such alternative theories offer a foil against which to test our confidence in the orthodox theory. © 1990 The American Physical Society.