Top Quark Forward-Backward Asymmetry and Same-Sign Top Quark Pairs

TL;DR

This paper investigates whether a non-universal Z' model can explain the Tevatron top quark forward-backward asymmetry by analyzing its implications for same-sign top pair production at the LHC.

Contribution

It assesses the discovery potential of same-sign top pairs at the LHC to test the Z' model as an explanation for the asymmetry.

Findings

No same-sign top signal with 1 fb$^{-1}$) excludes Z' as sole explanation.

Z' couplings must be large to match asymmetry, leading to detectable signals.

Early LHC data can test the Z' hypothesis effectively.

Abstract

The top quark forward-backward asymmetry measured at the Tevatron collider shows a large deviation from standard model expectations. Among possible interpretations, a non-universal $Z^\prime$ model is of particular interest as it naturally predicts a top quark in the forward region of large rapidity. To reproduce the size of the asymmetry, the couplings of the $Z^\prime$ to standard model quarks must be large, inevitably leading to copious production of same-sign top quark pairs at the energies of the Large Hadron Collider (LHC). We explore the discovery potential for $tt$ and $ttj$ production in early LHC experiments at 7-8 TeV and conclude that if {\it no} $tt$ signal is observed with 1 fb$^{-1}$ of integrated luminosity, then a non-universal $Z^\prime$ alone cannot explain the Tevatron forward-backward asymmetry.