We study the development of the mass matrix elements (Yukawa couplings) by integrating the renormalization group equations numerically. We find that the masses for a heavy fourth generation converge to values close to 200 GeV, the mass difference mT-mB ≈ (few) GeV. For realistic solutions where the Cabibbo mixing between the fourth and third generations is small, the top quark mass is limited from above by 60 GeV. Finally, we introduce the SU(5) condition for a charged heavy lepton and find that its mass is limited between 43 and 77 GeV.
Bibliographical noteFunding Information:
Two of us (EAP and JWH) wish to thank the Institute of Theoretical Physics in Santa Barbara and EAP the Unwersity of Wisconsin for the hospitality during the early stages of this work. The work was supported in part by a grant of the Bundesministerium ffir For-schung und Technolog~e. This material is also based upon work supported in part by the National Science Foundation under grant no. pht 77-2708, supplemented by funds from the National Aeronautics and Space Administration.