Theoretical and experimental update on a model featuring a second Z-boson

Abstract

An update is provided on theoretical and experimental aspects of a simple extension of the standard model featuring right-handed neutrinos and a second neutral gauge boson (Z′). We identify an ambiguity which a priori exists in the definition of electric charge in this model, and show spontaneous symmetry breaking can resolve it. We then re-analyse the experimental bounds on the mass of Z′ in the light of recent measurements of the standard Z boson mass and width at LEP and SLC. We find that the lower bound at 90% confidence level for the Z′ mass is 460 GeV. © 1990.