The Z′ reconsidered

Abstract

We consider the extension of the standard model with an arbitrary number of U(1) gauge fields coupled to baryon‐minus‐lepton number and/or hypercharge. Under the assumption that Abfb from the LEP1 experiment is an unlucky fluctuation, we find a mild indication for the presence of such fields in the precision electroweak data. A relatively large range of the Higgs boson mass is allowed. However we point out that the above assumption is controversial and not generally accepted in the community. We discuss the phenomenology of the extra U(1) fields.