THE DYNAMICAL MODELS AND THE $Z \rightarrow b\bar{b}$ ASYMMETRY

Motivated by the 3.2σ(1.4σ) deviations between the recent experimental value for and the standard model (SM) prediction, we examine the effect of new physics (NP) on the couplings and . First we focus our attention on the dynamical models. Then, using effective Lagrangian techniques, we discuss the corrections of NP to and . We find some kinds of NP which might explain the recently experimental data about Rb and . However, the free parameters of these kinds of NP must be severely constrained.