Model independent analysis of top quark forward-backward asymmetry at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$

TL;DR

This paper calculates the top quark forward-backward asymmetry and related observables at the Tevatron and LHC considering dimension-six operators, showing NLO QCD corrections are significant and that LHC can detect new physics effects.

Contribution

It provides the complete NLO QCD calculations of top quark asymmetries induced by dimension-six operators up to $ ext{O}(rac{ ext{ extasciitilde} ext{a}_s^2}{ ext{Lambda}^2})$, including scale dependence reduction.

Findings

NLO QCD corrections alter $A_{FB}$ and cross sections by about 10%.

NLO corrections significantly reduce scale dependence.

LHC has potential to observe new physics effects in charge asymmetry.

Abstract

We present the complete calculations of the forward-backward asymmetry ($A_{\rm FB}$) and the total cross section of top quark pair production induced by dimension-six four quark operators at the Tevatron up to $\mathcal{O}(\as^2/\Lambda^2)$. Our results show that next-to-leading order (NLO) QCD corrections can change $A_{\rm FB}$ and the total cross section by about 10%. Moreover, NLO QCD corrections reduce the dependence of $A_{\rm FB}$ and total cross section on the renormalization and factorization scales significantly. We also evaluate the total cross section and the charge asymmetry ($A_{\rm C}$) induced by these operators at the Large Hadron Collider (LHC) up to $\mathcal{O}(\as^2/\Lambda^2)$, for the parameter space allowed by the Tevatron data. We find that the value of $A_{\rm C}$ induced by these operators is much larger than SM prediction, and LHC has potential to discover these NP effects when the measurement precision increases.