Simple model of fourth-generation fermions

Abstract

If the mass ratios of the charged leptons, the charge -(1/3) and (2/3) quarks are roughly the same in each generation (except the first one), the present experimental limits on the fourth lepton mass and on the deviation of the electroweak ρ parameter from its tree-level value will lead us to expect that such fourth-generation fermions, if they exist, will have mass values in a narrow range. The phenomenological implications of this simple model including the production and decay properties of the seventh (charge -(1/3)) quark with mass ≊60 GeV and the contribution by the eighth (charge (2/3)) quark with mass ≊450 GeV to higher-order effects such as the kaon CP impurity parameter ε are discussed.