Diquark contributions to Top quark charge asymmetry at the Tevatron and LHC

We study contributions of a scalar diquark particle in a color representation of anti-triplet and sextet to the top quark pair production at the Tevatron and the Large hadron collider (LHC). The model can give Forward-Backward (FB) asymmetry at the Tevatron while can avoid the same sign top quark production at the LHC by assuming the top-number conserving diquark couplings. We study compatibility between the large positive FB asymmetry observed at the Tevatron and non-observation of the charge asymmetry at the LHC, by including contributions from the single and pair production of diquarks. We find that the whole parameter space of the models can soon be explored at the LHC by measuring the total t-tbar production cross section and the inclusive charge asymmetry with smaller uncertainties. In addition, we compare the statistical significance of the charge asymmetry measured at the LHC with that of the optimal observable of the subprocess FB asymmetry, and find that they are comparable even when we ignore the uncertainty in the parton distribution functions.