Non-resonant New Physics in Top Pair Production at Hadron Colliders

TL;DR

This paper investigates how top quark pair production at hadron colliders can reveal non-resonant new physics effects using an effective field theory approach, focusing on dimension-six operators and collider constraints.

Contribution

It provides a comprehensive analysis of top-philic dimension-six operators' impact on top pair production observables and assesses LHC's potential to constrain these operators.

Findings

The gluon fusion process is mainly affected by the chromo-magnetic moment operator.

LHC can constrain this operator with about 20% precision on the total cross section.

The approach is relevant for models of Higgs and top compositeness.

Abstract

We use top quark pair production as a probe of top-philic non-resonant new physics. Following a low energy effective field theory approach, we calculate several key observables in top quark pair production at hadron colliders (e.g., total cross section, ttbar invariant mass distribution, forward-backward asymmetry, spin correlations) including the interference of the Standard Model with dimension-six operators. We determine the LHC reach in probing new physics after having taken into account the Tevatron constraints. In particular, we show that the gluon fusion process gg -> ttbar which remains largely unconstrained at the Tevatron is affected by only one top-philic dimension-six operator, the chromo-magnetic moment of the top quark. This operator can be further constrained by the LHC data as soon as a precision of about 20% is reached for the total ttbar cross-section. While our approach is general and model-independent, it is particularly relevant to models of Higgs and top compositeness, which we consider in detail, also in connection with ttbar ttbar and ttbar bbbar production.