BOUNDS ON THE RENORMALIZED COUPLINGS IN AN SU(2)L CIRCLE-TIMES SU(2)RSYMMETRICAL YUKAWA MODEL

The vacuum stability lower bound on the mass of the Higgs boson is num erically investigated in an SU(2)L x SU(2)R symmetric Yukawa model, wh ich describes two heavy degenerate fermion doublets in the limit of va nishing gauge couplings. The values for the lower bound are in good ag reement with those obtained from an integration of the one-loop beta-f unctions, although the couplings are strong. The upper bound on the fe rmion mass and renormalized Yukawa coupling is also determined in the part of bare parameter space where reflection positivity has been prov en.