Implications of the Neutral Current Data for the Standard Model and for Grand Unification

摘要

All the most recent experimental data on neutral currents are used as constraints to determine the weak mixing angle within the framework of the standard SU(2) x U(1) model of electroweak interactions. Assuming that no superheavy Higgs bosons or fermions exist, we find sin exp 2 THETA/sub W/ = 0.238+-0.011 (chi exp 2 / = 20.7/24). If superheavy fermions of mass M/sub F/ exist, the data determine a confidence region in the (M/sub F/,sin exp 2 THETA/sub W/)-space. These results are in some disagreement with the SU(5) grand unification scheme, given the currently known proton lifetime. Within SU(2)/sub L/ x SU(2)/sub R/ x U(1) gauge models the lighter Z boson mass is predicted to be 84.4 + 3.2 - 2.5 GeV, all other parameters being free. (Atomindex citation 11:542798)