INCLUSION OF Z-]B(B)OVER-BAR VERTEX CORRECTIONS IN PRECISION ELECTROWEAK TESTS ON THE SP(6)(L)-X-U(1)(Y) MODEL

We extend our previous work on the precision electroweak tests in the Sp(6)L x U(1)Y family model to include for the first time the importan t Z --> b (b) over bar; vertex corrections encoded in a new variable e psilon(b), utilizing all the latest LEP data. We include in our analys is the one-loop EW radiative corrections due to the new bosons in term s of epsilon(1,b) and Delta Gamma(Z). We find that the correlation bet ween epsilon(1) and epsilon(b) makes the combined constraint much stro nger than the individual ones. The model is consistent with the recent CDF result of m(t) = 174 +/- 10 (13)(-12) GeV, but it cannot accommod ate m(t) greater than or similar to 195 GeV.