Top Quark Asymmetries and Unparticle Physics

TL;DR

This paper investigates whether vector unparticle physics can simultaneously explain the top quark forward-backward asymmetry observed at the Tevatron and the charge asymmetry at the LHC, while remaining consistent with other collider measurements.

Contribution

It demonstrates that a specific parameter space of vector unparticles can reconcile the Tevatron asymmetry with LHC charge asymmetry and collider constraints.

Findings

Identifies unparticle parameter regions fitting $A_{FB}$ and charge asymmetry.

Shows compatibility with dijet resonance search constraints.

Highlights tension and possible solutions in unparticle models.

Abstract

Among different measured observables of top-antitop quark pairs at hadron colliders, the forward-backward asymmetry ($A_{\text{FB}}$) measured by the CDF and D0 collaborations has inconsistency with the Standard Model prediction. The measured forward-backward asymmetry grows with $t\bar{t}$ invariant mass. Several new physics models have been proposed to explain this deviation. We consider the consistency of the parameter space of vector unparticle (in Flavor-Conserving scenario) with the existing $t\bar{t}$ production measurements. In particular, we look at the total cross sections at the LHC and Tevatron, differential cross section with $t\bar{t}$ invariant mass, and the LHC charge asymmetry to identify the regions in parameter space that can give the desired top $A_{\text{FB}}$ observed by the Tevatron. We show that in spite of the intrinsic tension between the LHC charge asymmetry and $A_{\text{FB}}$, there exists a region in the unparticle parameters space where the top $A_{\text{FB}}$ and the LHC charge asymmetry are satisfied simultaneously. Finally, we show that the consistent region with $t\bar{t}$ observables is consistent with the constraints coming from the dijet resonance searches.