ISOSPIN MULTIPLET STRUCTURE IN ULTRAHEAVY FERMION BOUND-STATES

The coupled Bethe-Salpeter bound state equations for a QQBAR system, w here Q =(UD) is a degenerate, fourth generation, superheavy quark doub let, are solved in several ladder approximation models. The exchanges of gluon, Higgs, and Goldstone modes in the standard model are calcula ted in the ultraheavy quark limit where weak gamma, W+/-, and Z0 contr ibutions are negligible. A natural I =0 and I = 1 multiplet pattern is found, with large splittings occurring between the different weak iso spin states when M(Q), the quark masses, are larger than values in the range 0.4 TeV < M(Q) < 0. 8 TeV, depending on which model is used. Co nsideration of ultraheavy quark lifetime constraints and U-D mass spli tting constraints are reviewed to establish the plausibility of lifeti me and mass degeneracy requirements assumed for this paper.