Top Quarks, Axigluons and Charge Asymmetries at Hadron Colliders

TL;DR

This paper investigates how axigluons, hypothetical particles coupling to quarks, can cause measurable charge asymmetries in top-antitop quark production at hadron colliders, providing new ways to detect or constrain axigluons.

Contribution

It introduces a new observable for charge asymmetry, updates previous asymmetry analyses, and sets a lower mass limit for axigluons based on recent collider data.

Findings

A new observable is more sensitive to axigluons than the forward-backward asymmetry.

A lower limit of 1.2 TeV on axigluon mass is established from Tevatron data.

Charge asymmetry at LHC can probe larger axigluon masses than dijet mass distributions.

Abstract

Axigluons are colored heavy neutral gauge boson that couple to quarks through an axial vector current and the same strong coupling as gluons. The most important model-independent manifestation of axigluons is the generation of a forward--backward asymmetry in top-antitop quark production at $p\bar{p}$ collisions which originates from the charge asymmetry. We update our previous analysis for the inclusive QCD induced forward--backward asymmetry and define a new observable which is more sensitive to the effect than the forward--backward asymmetry. Furthermore, we find a lower limit of 1.2 TeV at 90% C.L. on the axigluon mass from recent measurements of the asymmetry at Tevatron. Also at LHC, the charge asymmetry is sizable in suitably selected samples. We evaluate this asymmetry in the central region for different selection cuts and show that, like at Tevatron, the charge asymmetry can probe larger values of the axigluon mass than the dijet mass distribution.