ar X iv : h ep - p h / 02 04 05 7 v 1 4 A pr 2 00 2 The dynamical models and the Z → bb̄ asymmetry

Motivated by the 3.2σ(1.4σ) deviations between the recent experimental value for AFB(Rb) and the standard model(SM) prediction, we examine the effect of new physics(NP) on the Zbb̄ couplings g L and g b R. First we focus our attention on the dynamical models. Then, using effective lagrangean techniques, we discuss the corrections of NP to g L and g b R. We find some kinds of NP might explain the recently experimental data about Rb and A b FB. However, the free parameters of these kinds of NP must be severely constrained. PACS number(s): 12.60Cn,12.60.Nz,13.38.Dg This work is supported by the National Natural Science Foundation of China(I9905004), the Excellent Youth Foundation of Henan Scientific Committee(9911), and Foundation of Henan Educational Committee. E-mail:[email protected]