Top quark spin correlations and polarization at the LHC: standard model predictions and effects of anomalous top chromo moments

TL;DR

This paper provides precise Standard Model predictions for top-quark spin correlations and polarization at the LHC, and explores how anomalous top chromo moments could modify these observables, aiding in new physics searches.

Contribution

It offers the first comprehensive NLO calculations of top-spin observables including effects of anomalous chromo moments at the LHC energies.

Findings

Standard Model predictions for spin correlations and polarization at 7 and 8 TeV.

Identification of observables sensitive to top chromo moments.

Potential to distinguish real and imaginary parts of anomalous moments.

Abstract

A number of top-spin observables are computed within the Standard Model (SM), at next-to-leading order in the strong and weak gauge couplings for hadronic top-quark anti-quark (ttbar) production and decay at the LHC for center-of-mass energies 7 and 8 TeV. For dileptonic final states we consider the azimuthal angle correlation, the helicity correlation, and the opening angle distribution; for lepton plus jets final states we determine distributions and asymmetries that trace a longitudinal and transverse polarization, respectively, of the t and t-bar samples. In addition, we investigate the effects of a non-zero chromo-magnetic and chromo-electric dipole moment of the top quark on these and other top-spin observables and associated asymmetries. These observables allow to disentangle the contributions from the real and imaginary parts of these moments.