A set of top quark spin correlation and polarization observables for the LHC: Standard Model predictions and new physics contributions

TL;DR

This paper introduces a comprehensive set of observables based on leptonic angular correlations to probe top quark spin correlations and polarization at the LHC, including Standard Model predictions and potential new physics effects.

Contribution

It provides a complete framework of angular observables for top spin analysis, incorporating higher-order QCD, weak, QED corrections, and new physics contributions within an effective Lagrangian.

Findings

Standard Model predictions for angular correlations at 8, 13, 14 TeV

Quantitative effects of new physics operators on observables

Analysis of top polarization and charge asymmetry effects

Abstract

We consider top-antitop quark ($t{\bar t}$) production at the Large Hadron Collider (LHC) with subsequent decay into dileptonic and lepton plus jets final states. We present a set of leptonic angular correlations and distributions with which experiments can probe all the independent coefficient functions of the top-spin dependent parts of the $t{\bar t}$ production spin density matrices. We compute these angular correlations and distributions for LHC center-of-mass energies 8, 13, and 14 TeV within the Standard Model at next-to-leading order in the QCD coupling including the mixed QCD-weak corrections and for the transverse top-quark polarization and the $t{\bar t}$ charge asymmetry also the mixed QCD-QED corrections. In addition we analyze and compute the effects of new interactions on these observables in terms of a gauge-invariant effective Lagrangian which contains all operators relevant for hadronic $t{\bar t}$ production up to mass dimension six.