**2.2.2 The forward-backward asymmetry of top quark pairs**

In 2008, CDF showed a possible anomaly in the forward-backward asymmetry of the top quark, where AFB = 0.19± 0.07(stat.) ± 0.02(syst.) (Aaltonen et al., 2008). We have performed model independent analysis. Considering the s-, t-, and u- channel exchanges of spin-0 and spin-1 particles whose color quantum number is a singlet, octet, triplet or sextet, we study the region consistent with the CDF data at a one sigma level. We show the necessary conditions for the underlying new physics in a compact and effective way when those new particles are too heavy to be produced at the Tevatron. However, the results still affect the forward-backward asymmetry of top quark.
