Cross Section and Forward-Backward Asymmetry of $t\bar{t}$ Production in the Model with Four Color Symmetry

TL;DR

This paper investigates the effects of a four-color symmetry model on top-antitop production at the Tevatron and LHC, calculating contributions from new particles and setting mass limits based on experimental data.

Contribution

It provides the first detailed calculation of $Z'$-boson, scalar leptoquarks, and scalar gluons contributions to $tar{t}$ production within the four-color symmetry model, including loop effects.

Findings

Scalar gluons have a lower mass limit of about 320 GeV from Tevatron data.

Scalar gluon $F_1$ could be detectable at the LHC with over 3σ significance for masses below 990 GeV.

Loop effects can significantly enhance the contributions to the forward-backward asymmetry.

Abstract

The contributions to the cross section $\sigma_{t\bar{t}}$ and to the forward-backward asymmetry $A_{\rm FB}^{t \bar t}$ of $t\bar{t}$ production at the Tevatron from $Z'$-boson and scalar leptoquarks $S^{(\pm)}_a$ and scalar gluons $F_a$ predicted by the minimal model with four color quark-lepton symmetry are calculated. These contributions are shown to be small in tree approximation and can be significant with account of the 1-loop $gt\bar{t}$ effective vertex induced by the scalar doublets. The lower mass limit for scalar gluons $m_F \gtrsim 320\, GeV$ from the Tevatron data is obtained and it is shown that for $m_{F_1}\lesssim 990\,GeV$ the scalar gluon $F_1$ can be evident at LHC at the significance not less that $3\sigma$ (for $\sqrt{s}=14$ TeV, $L=10\,fb^{-1}$).