Looking for bSM physics using top-quark polarization and decay-lepton kinematic asymmetries

TL;DR

This paper investigates how top-quark polarization and decay-lepton kinematic asymmetries can be used to detect beyond Standard Model physics in top-antitop pair production at the Tevatron and LHC, employing asymmetry observables linked to lepton distributions.

Contribution

It introduces a set of asymmetry observables based on lepton kinematics that effectively distinguish between Standard Model and various bSM scenarios in top-quark production.

Findings

Asymmetries correlate with top polarization and charge asymmetries.

Proposed observables differentiate between SM and bSM models.

Effectiveness demonstrated with axigluon and diquark mediator models.

Abstract

We explore beyond Standard Model (bSM) physics signatures in the $l+jets$ channel of $t\overline{t}$ pair production process at the Tevatron and the LHC. We study the effects of bSM physics scenarios on the top quark polarization and on the kinematics of the decay leptons. To this end, we construct asymmetries using the lepton energy and angular distributions. Further, we find their correlations with the top polarization, net charge asymmetry and top forward backward asymmetry. We show that used together, these observables can help discriminate effectively between SM and different bSM scenarios which can lead to varying degrees of top polarization at the Tevatron as well as the LHC. We use two types of coloured mediator models to demonstrate the effectiveness of proposed observables, an $s$-channel axigluon and a $u$-channel diquark.