Forward Tevatron top quarks and backward LHC top quarks with associates

Abstract

The anomalous forward-backward asymmetry (${A}_{\mathrm{FB}}$) in $t\overline{t}$ production at the Tevatron is in apparent contradiction with the $t\overline{t}$ charge asymmetry (${A}_{\mathrm{C}}$) measurements at the LHC, which agree well with the standard model predictions. We argue that associated production of a state with $[u\overline{t}]$ flavor quantum numbers can lead to a sizable negative contribution to ${A}_{\mathrm{C}}$. Exchange of such a resonance in the $t$ channel would lead to positive contributions to ${A}_{\mathrm{FB}}$ and ${A}_{\mathrm{C}}$, as has been extensively discussed in the literature. Given the additional negative ${A}_{\mathrm{C}}$ contribution, both the Tevatron and LHC data can be naturally accommodated within this framework. A simple realization of this setup is the well known example of a ${Z}^{\ensuremath{'}}$ with flavor off-diagonal up-top couplings. We provide a detailed study of this model, demonstrating that it indeed reproduces the $t\overline{t}$ asymmetry data, and is compatible with other constraints, e.g., $t+\mathrm{\text{jet}}$ resonance searches, $t\overline{t}$ inclusive jet multiplicities, and atomic parity violation.