We study the possibilities of an extra Z boson expected from E6 grand unified theories by using the most recent e+e- annihilation data up to s =57 GeV. Limits on the mass and mixing angle for the extra Z boson are discussed. We find that the data fit well for an extra Z boson whose mass is in the range 100400 GeV and which has an appreciable vector coupling to charged leptons and down-type quarks. The upper mass bound is marginal such that it disappears at the 2 level even for the most favorable model (Z).
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)