Phenomenology of a light gluon resonance in top-physics at Tevatron and LHC

TL;DR

This paper analyzes the possibility of a light gluon resonance explaining Tevatron top-quark asymmetry results, showing compatibility with LHC data and highlighting key observables for future discrimination.

Contribution

It demonstrates that a light gluon resonance below 1 TeV can explain Tevatron anomalies and aligns with current LHC constraints, offering new insights into potential new physics.

Findings

Resonant new physics can fit Tevatron data for masses below 1 TeV.

Axial-like couplings are favored for light and top quarks.

Compatibility with LHC dijet and top pair production limits is shown.

Abstract

We present a phenomenological analysis of the recent Tevatron results on the $t \bar t$ forward-backward asymmetry and invariant-mass spectrum assuming a new contribution from an s-channel gluon resonance with a mass in the range from 700 to 2500 GeV. In contrast to most of the previous works, this analysis shows that for masses below ~1 TeV resonant New Physics could accommodate the experimental data. In general, we find that axial-like couplings are preferred for light and top quark couplings, and that only top quark couples strongly to New Physics. We find that composite model scenarios arise naturally from only phenomenological analyses of the experimental results. We show that our results are compatible with recent LHC limits in dijet and $t \bar t$ production, and find some tension for large resonance mass ~2.5 TeV. We indicate as best observables for discriminating a relatively light new gluon a better resolution in CDF forward-backward asymmetry, as well as the $t \bar t$ charge asymmetry and invariant-mass spectrum at the LHC.