Electroweak contribution to the top quark forward-backward asymmetry at the Tevatron

Abstract

The electroweak contributions to the forward-backward asymmetry in the production of top-quark pairs at the Tevatron are evaluated at $\mathcal{O}({\ensuremath{\alpha}}^{2})$ and $\mathcal{O}(\ensuremath{\alpha}{\ensuremath{\alpha}}_{s}^{2})$. We perform a detailed analysis of all partonic channels that produce an asymmetry and combine them with the QCD contributions. They provide a non-negligible addition to the QCD-induced asymmetry with the same overall sign, thus enlarging the standard model prediction and diminishing the observed deviation. For the observed mass-dependent forward-backward asymmetry a $3\ensuremath{\sigma}$ deviation still remains at an invariant-mass cut of ${M}_{t\overline{t}}>450\text{ }\text{ }\mathrm{GeV}$.