LHC Predictions from a Tevatron Anomaly in the Top Quark Forward-Backward Asymmetry

TL;DR

This paper explores how a new color octet vector boson could explain the top-quark forward-backward asymmetry observed at the Tevatron, fitting multiple experimental constraints and predicting detectable effects at the LHC.

Contribution

It introduces a comprehensive analysis of models with a color octet vector boson, identifying viable parameter spaces and linking them to specific coset models with potential LHC signatures.

Findings

Large allowed parameter space at high axigluon mass

Smaller viable region at low mass linked to coset model

Predicts discoverable LHC effects with minimal luminosity

Abstract

We examine the implications of the recent CDF measurement of the top-quark forward-backward asymmetry, focusing on a scenario with a new color octet vector boson at 1-3 TeV. We study several models, as well as a general effective field theory, and determine the parameter space which provides the best simultaneous fit to the CDF asymmetry, the Tevatron top pair production cross section, and the exclusion regions from LHC dijet resonance and contact interaction searches. Flavor constraints on these models are more subtle and less severe than the literature indicates. We find a large region of allowed parameter space at high axigluon mass and a smaller region at low mass; we match the latter to an SU(3)xSU(3)/SU(3) coset model with a heavy vector-like fermion. Our scenario produces discoverable effects at the LHC with only 1-2 inverse femtobarns of luminosity at 7-8 TeV. Lastly, we point out that a Tevatron measurement of the b-quark forward-backward asymmetry would be very helpful in characterizing the physics underlying the top-quark asymmetry.