Light colored scalars from grand unification and the forward-backward asymmetry in top quark pair production

TL;DR

This paper explores how light colored scalars from an SU(5) GUT model can simultaneously explain the top quark pair production cross section and forward-backward asymmetry observed at Tevatron, with specific mass predictions and experimental signatures.

Contribution

It introduces a specific SU(5) GUT model with light scalars that links proton decay constraints to top quark asymmetry explanations, providing a unified theoretical framework.

Findings

Both the t t̄ cross section and asymmetry are explained within the model.

The preferred mass for the scalar Delta_6 is around 400 GeV.

Delta_1 is constrained to have a mass around the TeV scale.

Abstract

The experimental results on the t bar t production cross section at the Tevatron are well described by the QCD contributions within the standard model, while the recent measurement of the forward-backward asymmetry cannot be accounted for within this framework. We consider light colored scalars appearing in a particular SU(5) GUT model within the 45-dimensional Higgs representation. A virtue of the model is that it connects the presence of a light colored SU(2) singlet (Delta_6) and a color octet weak doublet (Delta_1) with bounds on the proton lifetime, which constrain the parameter space of both scalars. We find that both the t bar t production cross section and the forward-backward asymmetry can be accommodated simultaneously within this model. The experimental results prefer a region for the mass of Delta_6 around 400 GeV, while Delta_1 is then constrained to have a mass around the TeV scale as well. We analyze possible experimental signatures and find that Delta_6 associated top production could be probed in the t bar t + jets final states at Tevatron and the LHC.