Top Quark Forward-Backward Asymmetry in the Large Invariant Mass Region

TL;DR

This paper explains the observed top quark forward-backward asymmetry at high invariant mass regions using a proposed $W'$ boson in a t-channel exchange, predicting its detectability at Tevatron and LHC.

Contribution

The paper introduces a $W'$ boson model to account for the large invariant mass asymmetry and demonstrates its potential for direct detection at collider experiments.

Findings

The $W'$ boson explains the enhanced asymmetry in large $M_{tar t}$ and $| riangle y|$ regions.

The $W'$ can be produced with a top quark at Tevatron and LHC, with observable signals.

Predicted $W'$ signals are detectable with current collider luminosities.

Abstract

The forward-backward asymmetry (FBA) in top-pair production that was observed in 2008 gets a boost in a recent CDF publication. Not only has the FBA further been confirmed, but also distributional preferences are shown. Strikingly, the FBA is the most sizable in the large $M_{t\bar t}$ invariant mass region and in the large rapidity difference $|\Delta y|$ region. Here we used our previously proposed $t$-channel exchanged $W'$ boson to explain the new observations. We show that a new particle exchanged in the $t$-channel generically gives rise to such observations. Furthermore, we show that the proposed $W'$ can be directly produced in association with a top quark at the Tevatron and the LHC. We perform a signal-background analysis and show that such a $W'$ is readily observed at the Tevatron with a 10 fb$^{-1}$ luminosity and at the LHC-7 with just a 100 pb$^{-1}$ luminosity.