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

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.