Implications of the Rb anomaly on Zt¯t couplings in standard ETC models

In standard ETC models the Rb anomaly is explained by a delicate balance between the opposing effects of sideways and diagonal ETC interactions. The aim of this article is to study the implications of this explanation and the CDF value for mt on ztt̄ couplings where the sideways and diagonal ETC effects interfere constructively. We find that for ms = m 2 d and δRb ≈ .0063, the vector and axial vector form factors for ztt̄ vertex are modified by 16% and 6% respectively from their SM values. The efficiency of probing these deviations at NLC through polarization and angular correlation studies in tt̄ pair production is also considered.