Top quark forward-backward asymmetry from the $3-3-1$ model

TL;DR

This paper investigates how the minimal 3-3-1 model, featuring a new neutral gauge boson with flavor-changing couplings, can explain the Tevatron's top quark forward-backward asymmetry without disrupting standard model predictions for cross sections.

Contribution

It demonstrates that the 3-3-1 model can account for the observed asymmetry through both s- and t-channel contributions, aligning with experimental data while maintaining standard model consistency.

Findings

The 3-3-1 model can explain the asymmetry with specific Z' mass ranges.

The model's predictions for cross section and invariant mass distribution match experimental results.

It reinforces the 3-3-1 model as a viable candidate for new physics in top quark production.

Abstract

The forward-backward asymmetry $A_{FB}$ in top quark pair production, measured at the Tevatron, is probably related to the contribution of new particles. The Tevatron result is more than a $2\sigma$ deviation from the standard model prediction and motivates the application of alternative models introducing new states. However, as the standard model predictions for the total cross section $\sigma_{tt}$ and invariant mass distribution $M_{tt}$ for this process are in good agreement with experiments, any alternative model must reproduce these predictions. These models can be placed into two categories: One introduces the s-channel exchange of new vector bosons with chiral couplings to the light quarks and to the top quark and another relies on the t-channel exchange of particles with large flavor-violating couplings in the quark sector. In this work we employ a model which introduces both s- and t-channel nonstandard contributions for the top quark pair production in proton antiproton collisions. We use the minimal version of the $SU(3)_C \otimes SU(3)_L \otimes U (1)_X$ model (3-3-1 model) that predicts the existence of a new neutral gauge boson, called $Z^\prime$. This gauge boson has both flavor-changing couplings to up and top quarks and chiral coupling to the light quarks and to the top quark. This very peculiar model coupling can correct the $A_{FB}$ for top quark pair production for two ranges of $Z^\prime$ mass while leading to cross section and invariant mass distribution quite similar to the standard model ones. This result reinforces the role of the 3-3-1 model for any new physics effect.