Model-independent analysis of forward-backward asymmetry of top quark production at the Tevatron

We perform a model independent analysis on $q\bar{q}\to t\bar{t}$ using an effective lagrangian with dim-6 four-quark operators, and derive necessary conditions on new physics that are consistent with the $t\bar{t}$ production cross section %(${\sigma }_{t\bar{t}}$) and and the forward-backward (FB) asymmetry ($A_{\mathrm{F}\mathrm{B}}$) measured at the Tevatron. We also propose a new FB spin-spin correlation that is strongly correlated with the $A_{\mathrm{F}\mathrm{B}}$, and discuss possible new physics scenarios that could generate such dim-6 operators.